[AprilPearl]

Another possibility is that he is nibbling as a natural behaviour. Hamsters have poor eyesight so will sniff/taste things that they gone across, and biting is instinctual as they are rodents. He doesn't know that the biting is hurting you. It doesn't sound as though he is nipping from fright if he's nit breaking the skin. He may just be chewing on you as he would any other object. Hamsters usually learn to stop biting if you adjust move your hands every time they prepare to/or do bite. Just move the area of skin they are biting away from them and repeat if they find a new spot. It's best to not let nibbling become an ingrained habit.