So it’s just when he gets up? Not when you move? Or do you move when he’s getting up? And it’s just a nip that hurts, no blood drawn.
If that is the case that it sounds like it could be that he’s finished with the affection session, and nips at you to move out of the way. Or he could be nipping as a way to say more.
In this situation you should let out a high pitched screech. This is telling him that nipping is too hard. And if you REALLY want to tell him in “bunny body language” that you didn’t like that, you can sit up and face your back to him, but keep looking over your shoulder to just turn slightly to let him know it’s okay to approach. He may approach or walk away.
This what bunnies actually do to each other and to us, when they’ve are offended by something.
Be prepared for stranged looks from the people around you, and them thinking you’ve gone completely bonkers. Just hold your head up high with dignity and tell them you are having a serious chat with your bunny at the moment! (it just happens to be in body language only) 
You have to do this everytime he nips. Hopefully he will soon his nips will become much ligher, or he’ll just nudge you with his nose instead.
Keep us updated.