Anyone Call This Overbet?

Had me totally confused. I don't want commentary on the flop miniraise because it often confused villain to shut down.

Bodog $12. Average ~6k. I've got my standard huge stack of 16k [img]/images/graemlins/tongue.gif[/img], but unfortunately to my left is an 11k stack and a 13k stack. Blinds 200/400. Everyone else at the table is pretty short (1k-6k, mostly ~3k) and I've been a big mean bully, stealing 2-3 times an orbit and calling all ins with pot odds with absolute crap. Everyone's read on me is probably that I'm a lucky donky.

My plan was to only raise a good hand on the button because I didn't need to get sheriffed by a big stack (I thought they'd be much more likely to call me outta the blinds). Anyway, I picked up A4o, it folded to me, and I raised to 1k. SB folds, BB calls.

Flop: 25A, 2 diamonds (the A is of diamonds)
SB bets minimum
I raise minimum

Turn: 4o
SB bets min
I call

River: 2o
Villain pushes

Anyone call? Does he really do this with a 2 or a 3? Did he flop a set and slowplay it? My first thought was a missed flush draw.