im all in in a heartbeat with that small raise......AA won't risk you folding the hand to a min raise over your 1.50....that was a positional bet, with the guy knowing he wanted to lead bet the flop with the lower PP, risk of AK on the flop...He cna still bet an A,K on the flop feeling like he is coming from strength....
If he had AA there he played it well, disguised his hand.....