Interesting hand - up for discussion

Live $200 max buy-in, 2/5 blinds. It was about 4 hours in, and I had built my stack up to about $750 when the following hand took place.

I'm in CO+1 w/ A [img]/images/graemlins/spade.gif[/img] Q [img]/images/graemlins/diamond.gif[/img]
EP limper, MP limper - I raise to $25. SB (good player with about $475) calls, BB folds, EP limper folds, MP limper calls.

Flop ($95) - Q [img]/images/graemlins/club.gif[/img] 4 [img]/images/graemlins/heart.gif[/img] 5 [img]/images/graemlins/spade.gif[/img]
MP checks, I bet $60, SB calls, MP folds.

Turn ($215) - 2 [img]/images/graemlins/heart.gif[/img]
SB bets $100. I think for awhile, then call.

River ($415) - 3 [img]/images/graemlins/club.gif[/img]
SB bets $250 (leaving him about $60). Hero calls.

This was a pretty standard hand for our table until the turn. I was somewhat worried about his call on the flop - he would have had simply called with a set or a big pair - but I had been making continuation bets like that all night, and I felt like he was probably testing me. His bet on the turn threw me off, and I called because I thought he was weak (he had won a number of pots making this exact play). Plus, he likely would have check-raised w/ any strong holding. The call on the river was tough - I tried to figure this hand out and I simply couldn't figure a hand with a 6 in it that he could have, given his lead bet on the turn. Maybe the 2 on the turn made his hand w/ A3 (I couldn't imagine him playing 36), or maybe he flopped a set and decided to push it on the turn. In either case, I would be either tied or ahead w/ my wheel. If he had 66, I couldn't see him leading out on the turn.

I'll post the results of the hand after receiving comments. Thanks.