I don't have any objection. It's a draw-heavy board so you might raise more on the turn. I think the bet on the river is good. Don't be too scared of the A... If you bet less or check here, he might raise with 67, 3x realizing you had an overpair to the board and are afraid he hit the A.
Ax is certainly a very possible hand. Many players don't like to give up Ax, plus they got a straight draw here, so... virtually the nuts. But still.