Dog Health Questions? Ask a Dog Vet for Answers ASAP
This depigmentation of the lips and nose can be perfectly normal. If the skin is otherwise normal (ie. no raised lesions, not itchy, the skin on the pink part of the nose matches the pigmented area), then I wouldn't worry about it at all.
There is a condition call impetigo that I see periodically. Most of the cases has been in Rottweilers, but it can occur in other breeds, too. Any dark area can become depigmented. Sometimes the color comes back, sometimes it doesn't.
But if you notice any crusting, scabs, irritation, etc, then I would take Toby in to your regular vet.