[lilzeus]

From the looks of it, he is on a draw. I wouldnt say he has hit a set or 2 pair. A set or 2 pair from the SB is almost always an automatic check/raise to the big preflop aggressor, not a pot sized bet(like he is trying to protect against a flush draw). He could have top pair with a flush draw.
I guess I am the only one that thinks you should raise here rather than wait for the turn. You said 'sometimes' he will just call your raise. Well, this particular sometime you have AA so I think you have to raise him to get a better idea of where you are at and also to make him pay to draw.