I've also had similar problems. My son is non verbal and he bites me. Not often, and only me, but hard enough to draw blood last time. Last time, I picked him up to go change his diaper and he was in a fine mood, just reached out and clenched his teeth on me and bit. It's times like this, when I'm at a loss, because I can't pin point it to any emotion like anger. I can understand he's angry at me and can't communicate, but when he seems happy and just bites??

MyZett is clearly on the right track here. Most behaviors happen for a reason, even though it can be hard to figure out what the reason is. If it is to get attention, then you need to figure out how to make sure it does not get attention. See if you can ignore it long enough to redirect it into a preferred activity. If he needs attention, then make sure he gets more attention and better attention by coming up to you and talking, or if he is non-verbal, touching your hand.

Even reacting by saying "ow!" can be reinforcing, because the cause and effect is a reward: It implies control over his environment which he does not get in some other ways.

If he is just looking for the sensory feedback, then try to find a squishy ball that he can play with instead. This is doubtful, though, because if it were sensory, he would also be pinching himself, or displaying other sensory-seeking behaviors.