[Engel]

Moving cage is the same as changing home so he may need more time to settle in again like you did when you got him.

If he's in bed when you rustle the bedding it may be that you startled him or woke him up. How do you pick him up? If grabbing from above it mimics a predator and he'll bite to defend himself. If you trap him in a corner he'll bite because he can't run away.

Positive reinforcement is key. Find something he likes like sunflower seeds as Dessi mentioned. What I did with my ham was I put some of his mix in my hand and lie my hand flat in the bottom of the cage. He'll want that food eventually and keeps his mouth busy so he can't bite you. Do this a couple of times a day (small amounts of food so you don't overfeed him). Then put less and less on your hand and leave your empty hand in there. May nibble some crumbs off but shouldn't be painful.

If he lunges it's aggression. If this continues its probably best to leave him be and handle him on his terms. He may not like to be handled and rather be left to hamster