He sounds fine. Mine is an early '10 and he's only 25". As long as he is healthy (eating shedding pooing eating) there is no need to worry about size.
I have a corn snake that I've had since Thanksgiving of 09', he's 33" and has the same girth as most corns that are only about 25", but his bones aren't showing at all, at first I was worried but you have to just accept that some snakes are smaller, some snakes are bigger
There's a guy on another forum I'm on who has a burm appropriately named NeverGrow--that snake is tiny compared to other burms his size! But he's healtyh so the owner is not concerned.