Hi guys, I got my M27 heads installed about a month ago. The lens always looked clean, dark and not discolored. Well, about a week ago, I noticed this. Any ideas on what it could be. I haven't touched the head since it was installed. It's been sealed since day one and I've tried wiping off whatever it is, with no success. I noticed the blemish after our jammerfest session in Buffalo. I'm at a a loss as to what it may be. One photo is the before and the other, after.