3yr Old Choc Lab w/ Graying Muzzle

Question
Is it normal for a 3 year old & neutered  chocolate lab to have a graying muzzle. I have been told what I suspect is an old wise tale which goes like this.  If the lab drinks out of a metal bowl he will gray if he drinks out of a plastic bowl he will not. and this will also turn nose from black to pink.  This sounds crazy, but he does drink from a metal bowl.  Is this just genetics or can I do anything to help prolong this graying? He is a great calm and loving dog who loves to play fetch! P.S. He also lays down and crosses his front paws as another poster had spoken of.

Answer
I highly doubt the water dish has much to do with it.  I wish I could think of a good example disproving it, but I can't.  How much sun the dog gets has a lot to do with the color of the nose.  I don't know that anything helps the graying.  

The leg crossing isn't common, but a few dogs do seem to do it.