What?! You didn't put a protective filter on this baby?

It's hard to tell from the picture. It's on the outer surface of the element, right? Has it etched into the glass or is it purely superficial? Have you tried rubbing alcohol? When did you notice it? Any idea what it might be?

Know before you send it to Nikon because most likely they will cite this is not covered under warranty. Of course, this might as well be the moment to say "what the hack" and throw it... (in my direction).

Nice shot by the way. Each lens has its characters so is this 牛头。