Yes, normal. If a surface, such as aluminum, has any type of coating applied to it, it is then susceptible to coming off and being scratched. It's no different than the paint on a car.
Seems an odd choice of material for a portable gadget that is going to be kept in bags/pockets.
My four year old car has been used as the manufacturer expects and I can safely say none of the paint has scratched or chipped off.