Is this colluding in a tourney I played on pokerstar?

I think colluders generally try to take other players' chips and not give one their own. Besides, this is a pretty low sample to determine a conclusion. You probably need hundreds of hands of guys playing similar games and showing up at the same tables consistently to make any kind of inference. Poker softwares are designed to look for such patterns, as well. My guess is that they aren't colluding.