[cypher]

It's quite common behaviour for hybrids really, some just grow out of it but some do persist a bit. It's usually just exploring more than anything else & I've found unless my nails are really short like they usually are they do like to chew on them!
Sometimes they do this weird thing that seems as though they're trying to drag your hand into the nest too!
I would just try gently moving your hand away for a moment when he does it but not much more to discourage it as long as he's not biting hard, he will most likely stop doing it or doing it so much with time.