He'll grow out of it, all the dogs I have ever had did eventually grow out of the chew on your hands stage.
I never did make a big deal out of it because I was always bad to play fight with them using my hands as they all loved it so much, but as they get older they kinda lose interest.
LOL my 6 year old poodle has been just a bit jealous since we got Binks that he has kind of reverted to puppyhood and also tries to play with my hand using his mouth, its so funny though as he will put his mouth over my hand with his mouth wide open and he never closes it, he just stands there with his mouth open.
