[CazicT]

You have a couple of thousand hands on him which means his postflop AF of 3 is more concrete than you usually have. This makes him Aggro.

An aggro player would probably raise you on the flop with AQ, although since you put a full PSB on maybe he decided to slow it down.

I think he could certainly have some kind of a flush draw.

He is tight preflop, yes, but he was looking at probably playing a multi-way pot so I wouldn't doubt that SC are in his range. Tightness PF doesn't necassarily mean tightness postflop, I think he could certainly call with a FD or SD facing a PSB.

Just my opinions of course.