Growing up long before the Internet and kydex holsters, I've always used leather for my guns. After using a Serpa holster for a few days, I've noticed marks on my slide from holstering/unholstering my gun everyday. It rubs off so I take it that its just plastic residue coming from the holster. After extended use, will the residue become less or will the rubs on the slide become more prominent? I had another gun I got in a trade that the same marks didn't rub off.