How long were you at the table?

What was your action? Were you raising a lot preflop? Did you take some of his money and put him on tilt?

Besides these questions I would say he may have had low pair or even AJ suited. He could have just been trying to make a move on you. You can't blame him for raising as there were 2 callers on the 3.50.

Few people are able to fold after someone min's over the top.. I think that you should have waited and then called. That way, the raise on his end would have came to the other two. I'm guessing that they would have folded but you never know. In addition, he would have bet on the flop, possibly shoved if you checked with a flop having two suited cards.

Good news is that you took it down.