my logic for not expecting villian to raise a set on the flop was that on a rainbow flop with a bet from the big blind he would want to get me to bet on later streets by just calling on the flop. Then again i rarely bet anything but big draws, so i wouldnt expect me to be drawing against a set once i bet the flop. I would've expected a turn raise, but from a set i would've expected a smooth call on the flop. The continued aggression (pot sized bets and bigger on turn and river) convinced me that he was trying to get me out, either because he figured i was drawing or he was bluffing. The pot sized river bet with no draws completed on board convinced me he was bluffing as i would expect a set to make some kind of value bet at that point.