LEAVE IT. OH GOD JUST LEAVE IT. LET IT GO!
Even if the roleplay is freaking awesome, those bad feelings eventually will taint your experience and make things a huge pain in the ass. EVEN if you're being mature about things and everyone is behaving. Little aggressions and problems always have a way of slipping out, even if it's just you ranting to a coplayer. And I can tell you, you coplayers and friends don't wanna listen to you complaining about it, especially if they don't have any problems with the GM or roleplay. (I have been in SO MANY of these situations and it's really frustrating. ;_;)
And even if you never complain or show any aggression yourself, you're still just torturing yourself slowly. D: That is how people turn in to bitter psychos. Never force yourself to interact with someone you dun like.