There is a condition called contact depigmentation and it can be transitory. Does he by any chance eat or drink from a plastic or rubber bowl ......have plastic or rubber toys?

There is also a condition called vitiligo in humans, and I'm sure it can happen in dogs too. Link below to plastic nasal dish dermititis.

Here is a link that might be useful: Dog pigmentation problems

Google Discoid Lupus. (Not SLE). It usually starts with loss of pigmentation on the nose and face and if it's minimal vitamin E supplements can help.

Calliope - we do not use plastic or rubber bowls...or toys as the Princess demands only soft squishy stuffed toys...

I have looked at vitiligo, looks similar but not the same. I also googled, can't find anything that really looks the same to me.

cynthia - I saw this one too - all the images I find by google look MUCH more extensive than what we have so I don't know if this is not it or if she might be in the very early stages.

Thanks to both of you for the ideas. I guess we'll be heading it to get it checked out to be sure it's not serious.

Probably not serious. Lupus is generally symmetrical. Probably not worse than UV damage.

Thank you everyone. We will watch. If it gets worse or seems inflamed or gives us other reason to become more concerned, we'll go see the vet. Otherwise, I think we'll just wait till our next visit and ask then.