If he's a late position poster then I guess you had no read on him. I think this was a case of "if he's an idiot I win, if he's decent I lose." Glad he was an idiot. So many people out there think their trips are good by definition. Glad to know that happens even at the $200 buy-in level. What a wonderful thing.

I wouldnt have reraised him either for the reasons already given. Once he raises you again, you have to call, but I would expect to lose the majority of times.

The reason you dont want to reraise is because you have to assume he doesnt have the 9 because he shouldnt have called your original flop bet with middle pair. You have to give a player the benefit of the doubt that hes decent until proven otherwise. Most times he will have a set (boat) in that situation.

You now have your proof.