Kind of a random question - we adopted 1.5 year old golden retriever in August and i was looking at a picture of him shortly after we brought him home. His nose was totally black, but I've noticed it is no longer totally black- it's like the black rubbed off or something! He eats and drinks out of stainless steel bowls - is this the cause, and if so, is this a bad thing? should he have plastic bowls?