Is it fine to use cases that fit tightly the aluminium MBP 2010?

[hajime]

Hello. I bought a computer case because of its style. It is not designed for the MBP 17" but it just fits. By that, I mean I can insert the laptop into the sleeve of the case and it fully covers it. However, there are frictions between the MBP and the case whenever I try to take out the computer or put it into the sleeve. I read that there is a layer of coating for the aluminum MBP. If I continue to use this case for 2-3 years, will the coating wears off over time? Will the frictions cause scratches to the MBP? I guess before I insert the laptop into the sleeve, I better make sure that there are no small items inside it. Thanks.