This is not a typical AOS Example. It looks like during the anodizing process there was not the proper rinse cycle on a few of our AOS's, some of the chemicals when not cleaned off will discolor. This is something we will most definitely take up with our anodizing company. If you cant remove this with a rag please PM us and we will be sure to get this taken care of. If you look at the actual body it is free of discoloration, it is simply a chemical on the surface and not the actual metal/anodize material. We have endlessly tested the durability of these coatings and they can withstand extreme temperatures. As always we will be here to support and help those in need!