Reporters noticed Miller was sitting in the back row of the NDP caucus instead of his usual seat closer to Horwath, who was not in the legislature Monday.
Miller is one of the NDP's most effective — and loudest — hecklers, and apparently he didn't like Horwath's request last Thursday to tone it down.
Miller isn't commenting on his conversation with Horwath, which was not picked up by Hansard, the official record of legislative debates.
NDP house leader Gilles Bisson insists Miller is not being punished, and says all seats in the legislature are good seats.
Bisson says the party wants to get away from loud heckling because it doesn't look respectful to the public.