Hi, new to this so be kind! Over the last few months we’ve been noticing a small black patch on my Labrador’s water line just below his eye. It’s not bothering him at all, not raised , seems to me like it’s some sort of pigmentation thing. Can these things just appear out of nowhere though? He’s almost 4 and it’s only been there the last 6 months or so. Any help would be great thanks!