What is this discoloration?

So I was wiping down my LCP II and noticed the extractor had some discoloration on its finish. It almost appears to be rust but I'm uncertain. It appears a bit more copper colored than the photo shows. It is only present on the extractor and doesn't appear to have any texture. Additionally, my other LCP II does not have this on the extractor. So I ask you, oh wise sages of THR, is this rust or just something funky with the finish? Many thanks!