Quick question: Every so often I'll have to unload an entire mag, usually because I like to rotate new mags by leaving them fully loaded for periods of time to break in the spring (this is especially true for my handgun mags). The casings develop some scratches and abraisions from being unloaded and then put back into another mag. Does this create a problem when they expand during firing? Should I worry about this at all?

No worries.

I didn't think it was a big deal.