I wouldn't have checked the river, I had him on JT, or J8 as well. What about checking the turn instead to see if he is serious about the hand or not. If it is an overpair or a set, At $25NL they get a little ansy about not getting money in on the turn, so a raise here will tell you more. He'll re raise push on the turn as fast as he does on the river because your not moving fast enough. The problem with $25NL is Overpairs are played like monsters to some of these guys.