Mikaela Hoover better be ok with boyfriend Nathan Fillion getting close with his co-stars!

The former "Firefly" actor was photographed acting really chummy with his "Castle" co-star Susan Sullivan while posing at a media presentation of "The Wait Is Over! 'Castle' Is Back!" in Beverly Hills on Monday. Wearing his trademark monochrome suit, the actor hugged and kissed Sullivan who looked pretty in a matching black-and-beige ensemble.

But not to worry Mikaela, the 42-year-old Edmonton, Alta.-born actor wasn't pulling a move on the 70-year-old actress! Sullivan plays Fillion's mother on the show so it's no wonder that the two are very affectionate with each other.

In fact, at a press event earlier in September, the actress sang her handsome co-star's praises, saying:

"Who wouldn't want Nathan Fillion in their life? He is the most delightful man you can imagine." Awww, we're melting in our seats!

Luckily for Nathan's girlfriend, she gets him all to herself! The 29-year-old actress has been dating the Twitter fan since 2010 and made quite the impression when she walked the Emmys 2013 red carpet with her beau.

Call us jealous!

nathan fillion

Love ya, Nathan:

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  • Nathan Fillion

    Actor Nathan Fillion (R) and guest attend the 2013 American Music Awards after party at Nokia Theatre L.A. Live on November 24, 2013 in Los Angeles, California. (Photo by Chelsea Lauren/AMA2013/Getty Images for DCP)

  • 2013 American Music Awards - Show

    LOS ANGELES, CA - NOVEMBER 24: Actors Nathan Fillion and Alicia Silverstone speak onstage during the 2013 American Music Awards at Nokia Theatre L.A. Live on November 24, 2013 in Los Angeles, California. (Photo by Kevin Winter/Getty Images)

  • 2013 American Music Awards - Arrivals

    LOS ANGELES, CA - NOVEMBER 24: Actor Nathan Fillion attends the 2013 American Music Awards at Nokia Theatre L.A. Live on November 24, 2013 in Los Angeles, California. (Photo by Jason Merritt/Getty Images)

  • Nathan Fillion, Alicia Silverstone

    Nathan Fillion, left, and Alicia Silverstone present the award for single of the year at the American Music Awards at the Nokia Theatre L.A. Live on Sunday, Nov. 24, 2013, in Los Angeles. (Photo by John Shearer/Invision/AP)

  • Nathan Fillion

    Nathan Fillion arrives at the 'Thor: The Dark World' - Los Angeles Premiere at the El Capitan Theatre on November 4, 2013 in Hollywood, California. (Photo by Steve Granitz/WireImage)

  • Nathan Fillion

    Actor Nathan Fillion arrives at the premiere of Marvel's 'Thor: The Dark World' at the El Capitan Theatre on November 4, 2013 in Hollywood, California. (Photo by Jason Merritt/Getty Images)

  • Nathan Fillion

    HOLLYWOOD, CA - NOVEMBER 04: Actor Nathan Fillion arrives at the premiere of Marvel's 'Thor: The Dark World' at the El Capitan Theatre on November 4, 2013 in Hollywood, California. (Photo by Jason Merritt/Getty Images)

  • Nathan Fillion

    (L-R) Actors Zachary Levi, Nathan Fillion and Tom Hiddleston arrive at the premiere of Marvel's 'Thor: The Dark World' at the El Capitan Theatre on November 4, 2013 in Hollywood, California. (Photo by Jason Merritt/Getty Images)

  • Nathan Fillion

    (L-R) Actors Zachary Levi, Nathan Fillion and Tom Hiddleston arrive at the premiere of Marvel's 'Thor: The Dark World' at the El Capitan Theatre on November 04, 2013 in Hollywood, California. AFP PHOTO/JOE KLAMAR (Photo credit should read JOE KLAMAR/AFP/Getty Images)

  • Nathan Fillion

    From left, Zachary Levi, Nathan Fillion and Tom Hiddleston arrive at the U.S. premiere of "Thor: The Dark World" at the El Capitan Theatre on Monday, Nov. 4, 2013, in Los Angeles. (Photo by Jordan Strauss/Invision/AP)

  • Nathan Fillion

    Zachary Levi, left, and Nathan Fillion arrive at the U.S. premiere of "Thor: The Dark World" at the El Capitan Theatre on Monday, Nov. 4, 2013, in Los Angeles. (Photo by John Shearer/Invision/AP)

  • Nathan Fillion

    Actor Nathan Fillion arrives at the The Paley Center For Media presents The Wait Is Over: "Castle" is Back on Monday, Sept. 30, 2013 in Beverly Hills, Calif.. (Photo by Paul A. Hebert/Invision/AP)

  • Nathan Fillion, Susan Sullivan

    Actors Nathan Fillion and Susan Sullivan arrive at the The Paley Center For Media presents The Wait Is Over: "Castle" is Back on Monday, Sept. 30, 2013 in Beverly Hills, Calif.. (Photo by Paul A. Hebert/Invision/AP)

  • Premiere Of The Film Arcade's "A.C.O.D." - Arrivals

    LOS ANGELES, CA - SEPTEMBER 26: Actor Nathan Fillion (L) and actress Mikaela Hoover attend the premiere of The Film Arcade's 'A.C.O.D.' at the Landmark Theater on September 26, 2013 in Los Angeles, California. (Photo by Jason Merritt/Getty Images)

  • Nathan Fillion, Mikaela Hoover

    Nathan Fillion, left, and Mikaela Hoover arrive at the 65th Primetime Emmy Awards at Nokia Theatre on Sunday Sept. 22, 2013, in Los Angeles. (Photo by Dan Steinberg/Invision/AP)

  • Nathan Fillion

    Nathan Fillion performs with dancers on stage at the 65th Primetime Emmy Awards at Nokia Theatre on Sunday Sept. 22, 2013, in Los Angeles. (Photo by Chris Pizzello/Invision/AP)

  • Nathan Fillion, Neil Patrick Harris, Sarah Silverman

    Nathan Fillion, from left, Neil Patrick Harris, and Sarah Silverman perform on stage at the 65th Primetime Emmy Awards at Nokia Theatre on Sunday Sept. 22, 2013, in Los Angeles. (Photo by Chris Pizzello/Invision/AP)

  • 65th Annual Primetime Emmy Awards - Arrivals

    LOS ANGELES, CA - SEPTEMBER 22: Actor Nathan Fillion arrives at the 65th Annual Primetime Emmy Awards held at Nokia Theatre L.A. Live on September 22, 2013 in Los Angeles, California. (Photo by Frazer Harrison/Getty Images)

  • HBO's Annual Primetime Emmy Awards Post Award Reception - Arrivals

    LOS ANGELES, CA - SEPTEMBER 22: Actor Nathan Fillion (L) and actress Mikaela Hoover attend HBO's Annual Primetime Emmy Awards Post Award Reception at The Plaza at the Pacific Design Center on September 22, 2013 in Los Angeles, California. (Photo by Michael Buckner/Getty Images)

  • Playboy And Universal Pictures' "Kick-Ass 2" Event At Comic-Con Sponsored By AXE Black Chill - Red Carpet

    SAN DIEGO, CA - JULY 19: Actor Nathan Fillion arrives at the Playboy and Universal Pictures' 'Kick-Ass 2' event at Comic-Con sponsored by AXE Black Chill on July 19, 2013 in San Diego, California. (Photo by Jason Merritt/Getty Images for Playboy)

  • Screening Of Lionsgate And Roadside Attractions' "Much Ado About Nothing" - Red Carpet

    HOLLYWOOD, CA - JUNE 05: Actor Nathan Fillion attends the screening of Lionsgate and Roadside Attractions' 'Much Ado About Nothing' on June 5, 2013 in Hollywood, California. (Photo by Jason Kempin/Getty Images)

  • Screening Of Lionsgate And Roadside Attractions' "Much Ado About Nothing" - Red Carpet

    HOLLYWOOD, CA - JUNE 05: Actors Clark Gregg, Nathan Fillion, Jennifer Grey and Amy Acker attend the screening of Lionsgate and Roadside Attractions' 'Much Ado About Nothing' on June 5, 2013 in Hollywood, California. (Photo by Jason Kempin/Getty Images)

  • 2013 WGAw Writers Guild Awards - Inside

    LOS ANGELES, CA - FEBRUARY 17: Host Nathan Fillion speaks onstage at the 2013 WGAw Writers Guild Awards at JW Marriott Los Angeles at L.A. LIVE on February 17, 2013 in Los Angeles, California. (Photo by Maury Phillips/Getty Images for WGAw)

  • The Entertainment Weekly Pre-SAG Party Hosted By Essie And Audi - Inside

    LOS ANGELES, CA - JANUARY 26: Actors Nathan Fillion and Tamala Jones attend the Entertainment Weekly Pre-SAG Party hosted by Essie and Audi held at Chateau Marmont on January 26, 2013 in Los Angeles, California. (Photo by Alexandra Wyman/Getty Images for Entertainment Weekly)

  • 70th Annual Golden Globe Awards - Press Room

    BEVERLY HILLS, CA - JANUARY 13: Presenters Lea Michele (L) and Nathan Fillion pose in the press room during the 70th Annual Golden Globe Awards held at The Beverly Hilton Hotel on January 13, 2013 in Beverly Hills, California. (Photo by Kevin Winter/Getty Images)

  • 39th Annual People's Choice Awards - Press Room

    LOS ANGELES, CA - JANUARY 09: Actor Nathan Fillion, winner of Favorite TV Drama Actor and Favorite TV Crime Drama for 'Castle,' poses in the press room at the 39th Annual People's Choice Awards at Nokia Theatre L.A. Live on January 9, 2013 in Los Angeles, California. (Photo by Jason Merritt/Getty Images)

  • "Much Ado About Nothing" Premiere - 2012 Toronto International Film Festival

    TORONTO, ON - SEPTEMBER 08: Actors Sean Maher (L) and Nathan Fillion attends the 'Much Ado About Nothing' premiere during the 2012 Toronto International Film Festival at The Elgin Theatre on September 8, 2012 in Toro (Photo by Sarjoun Faour Photography/Getty Images)

  • The Hollywood Reporter TIFF Video Lounge Presented By Canon - Day 2 - 2012 Toronto International Film Festival

    TORONTO, ON - SEPTEMBER 08: Guest (L) and Nathan Fillion attend The Hollywood Reporter TIFF Video Lounge Presented By Canon during the 2012 Toronto International Film Festival at Brassaii on September 8, 2012 in Toronto, Canada. (Photo by Todd Oren/Getty Images For The Hollywood Reporter)

  • Entertainment Weekly's 6th Annual Comic-Con Celebration Sponsored By Just Dance 4

    SAN DIEGO, CA - JULY 14: Actor Nathan Fillion (L) and director Joss Whedon attend Entertainment Weekly's 6th Annual Comic-Con Celebration sponsored by Just Dance 4 held at the Hard Rock Hotel San Diego on July 14, 2012 in San Diego, California. (Photo by Alberto E. Rodriguez/Getty Images for Entertainment Weekly)

  • "Firefly" 10 Year Anniversary Reunion Press Conference - Comic-Con International 2012

    SAN DIEGO, CA - JULY 13: Nathan Fillion speaks onstage at the 'Firefly' 10 Year Anniversary Reunion Press Conference during Comic-Con International 2012 held at the Hilton San Diego Bayfront Hotel on July 13, 2012 in San Diego, California. (Photo by Frazer Harrison/Getty Images)

  • "Firefly" 10 Year Anniversary Reunion Press Conference - Comic-Con International 2012

    SAN DIEGO, CA - JULY 13: Nathan Fillion speaks onstage at the 'Firefly' 10 Year Anniversary Reunion Press Conference during Comic-Con International 2012 held at the Hilton San Diego Bayfront Hotel on July 13, 2012 in San Diego, California. (Photo by Frazer Harrison/Getty Images)

  • Premiere Of Columbia Pictures' "The Amazing Spider-Man" - Arrivals

    WESTWOOD, CA - JUNE 28: Actor Nathan Fillion arrives at the premiere of Columbia Pictures' 'The Amazing Spider-Man' at the Regency Village Theatre on June 28, 2012 in Westwood, California. (Photo by Jason Merritt/Getty Images)

  • The Paley Center For Media's PaleyFest 2012 Honoring "Castle"

    BEVERLY HILLS, CA - MARCH 09: Actors Nathan Fillion and Stana Katic arrive to The Paley Center for Media's PaleyFest 2012 honoring 'Castle' at Saban Theatre on March 9, 2012 in Beverly Hills, California. (Photo by Alberto E. Rodriguez/Getty Images)

  • 2012 People's Choice Awards - Backstage And Audience

    LOS ANGELES, CA - JANUARY 11: Actors Alyson Hannigan and Nathan Fillion backstage during the 2012 People's Choice Awards at Nokia Theatre L.A. Live on January 11, 2012 in Los Angeles, California. (Photo by Christopher Polk/Getty Images for PCA)

  • Entertainment Weekly's 5th Annual Comic-Con Celebration Sponsored By Batman: Arkham City

    SAN DIEGO, CA - JULY 23: Actors Joel McHale (L) and Nathan Fillion (R) arrive at Entertainment Weekly's 5th Annual Comic-Con Celebration sponsored by Batman: Arkham City held at Float, Hard Rock Hotel San Diego on July 23, 2011 in San Diego, California. (Photo by Michael Buckner/Getty Images For Entertainment Weekly)

  • Spike TV's "2010 Video Game Awards" - Arrivals

    LOS ANGELES, CA - DECEMBER 11: Actors Nathan Fillion and Kate Luyben arrive at Spike TV's '2010 Video Game Awards' held at the LA Convention Center on December 11, 2010 in Los Angeles, California. (Photo by Frederick M. Brown/Getty Images)

  • 62nd Annual Primetime Emmy Awards - Show

    LOS ANGELES, CA - AUGUST 29: Actors Emily Deschanel (L) and Nathan Fillion speak onstage at the 62nd Annual Primetime Emmy Awards held at the Nokia Theatre L.A. Live on August 29, 2010 in Los Angeles, California. (Photo by Kevin Winter/Getty Images)

  • "Super" Panel - Comic-Con 2010

    SAN DIEGO - JULY 23: Actors Nathan Fillion and Rainn Wilson fight onstage at the 'Super' panel discussion during Comic-Con 2010 at San Diego Convention Center on July 23, 2010 in San Diego, California. (Photo by Kevin Winter/Getty Images)

  • 42nd Annual Academy Of Magical Arts Awards - Arrivals

    HOLLYWOOD - APRIL 11: Actors Nathan Fillion (L) and Kate Luyben attend the 42nd Annual Academy of Magical Arts Awards at Avalon Hollywood on April 11, 2010 in Hollywood, California. (Photo by David Livingston/Getty Images)

  • Paley Center For Media Presents An Evening With "Castle"

    BEVERLY HILLS, CA - MARCH 16: Actress Stana Katic and actor Nathan Fillion attend The Paley presentation of 'Castle' at The Paley Center for Media on March 16, 2010 in Beverly Hills, California. (Photo by Jason Merritt/Getty Images)

  • Serenity - In-Store Photocall

    LONDON - OCTOBER 06: Nathan Fillion, Summer Glau and Joss Whedon pose before meeing fans and signing copies of the DVD 'Firefly' at HMV Oxford Street on October 6, 2005 in London, England. (Photo by Chris Jackson/Getty Images)

  • "Serenity" UK Premiere - Arrivals

    LONDON - OCTOBER 05: Actress Summer Glau and Actor Nathan Fillion arrive at the UK Premiere of 'Serenity' at the Odeon West End on October 5, 2005 in London, England. (Photo by Gareth Cattermole/Getty Images)

  • Premiere of Universal Pictures' "Serenity" - Arrivals

    LOS ANGELES, CA - SEPTEMBER 22: (l-r) Sean Maher, Summer Glau, Joss Whedon, director Nathan Fillion, Adam Baldwin, pose at the Universal Pictures' Premiere of 'Serenity' held at Universal Studios on September 22, 2005 in Los Angeles, California. (Photo by Frazer Harrison/Getty Images)

  • 31st Deauville Film Festival - Serenity

    DEAUVILLE, FRANCE - SEPTEMBER 03: Actress Summer Glau and Nathan Fillion pose at the photocall for ?Serenity? at the 31st Deauville Festival Of American Film on September 3, 2005 in Deauville, France. (Photo by Francois Durand/Getty Images)

  • Premiere of "The Yes Men" - Arrivals

    HOLLYWOOD - SEPTEMBER 23: Actor Nathan Fillion and actress Andrea Robinson arrives to the premiere of United Artists' film 'The Yes Men' on the opening night of the Silver Lake Film Festival at the ArcLight Cinerama Dome September 23, 2004 in Hollywood, California. (Photo by Kevin Winter/Getty Images)

  • 29th Annual Saturn Awards

    LOS ANGELES - MAY 18: Actor Nathan Fillion attends the 29th Annual Saturn Awards presented by Cinescape May 18, 2003 at the Renaissance Hollywood Hotel in Los Angeles, California. (Photo by Jessica Silverstein/Getty Images)

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