It turns out there was no need to worry.
The 16-year-old from Saguenay led after qualifying and continued her dominance into the final to win gold in women's slopestyle on Friday.
"I'm really happy," said Fillion, who finished with a score of 81.50. "It's my first event of the season, so I wasn't sure if my shoulder would be OK."
Fillion pumped a fist in the air after her final run, and then had a quiet moment to herself near the base of the mountain.
"I was hoping for a podium," she said. "Now with the gold, it is really amazing ... it gives me a lot of confidence for the rest of the season."
Baily McDonald of Barrie, Ont., finished second with a score of 74.00, while Kennedi Deck of Grande Prairie, Alta., was third with 71.90 in the competition that sees athletes judged after going down a course that includes rails and jumps.
Christina Retson of Bedford, N.S., was second after qualifying, but she crashed on her first run of the final and was placed on a backboard before being taken to hospital.
There was no immediate update on her condition.
It ended up being a golden sweep for Quebec at the Tabor Mountain Ski Resort as Francis Jobin also topped the field in the men's competition.
"It was a really good day. I'm really happy about my runs," said the 16-year-old from Quebec City. "I'm excited to be able to represent Quebec and do my best.
"I wanted to win gold in Prince George, and I did."
Jobin scored 86.00, followed by Quinten Fast (84.70) of Agassiz, B.C., and Barrie's Coulton Conway (80.20).
Some of the athletes taking part in the multi-sport Canada Winter Games are expected to go on and represent their country on the international stage at some point — Olympic bronze medallist Mark McMorris competed for Saskatchewan in 2007 — and it's something that has crossed the minds of both Fillion and Jobin.
"I think every athlete's major goal is to go to the Olympics," said Fillion. "But there are many steps to get there."
Added Jobin: "I'm really happy with the result. If I can keep this up maybe one day I will be able to go to the Olympics and be a pro snowboarder."