First of all, sorry for the crappy cell pics. I can't seem to find my digital camera since I moved. I noticed this when I first got my Kimber(bought it used) and didn't really think much of it because it was only a little spot but it has gotten worse. I tried getting it of using the Hoppes #9 that I use to clean all my guns with but it didn't come off. What is it and how do I get it off?