Strange Dwarf Hamster Behaviour?

[Coneil3822]

Hello! I purchaced a Dwarf Hamster yesterday and he looks happy and healthy! The only thing that is worring me is that he keeps digging holes in the bedding and prefers to sit, lay and sleep on the plastic instead of on the bedding. I tried putting more bedding in and he just digs in the same spots all the way down to the plastic. Also he is always scratching at either the bottom of the cage or the plastic side walls, is this normal? Please help! Thank you, im new to this!!