It might be snow-nose...but in checking for a link to have you look at, I found this info:
Other causes of loss of nose color are vitaligo, snow nose, and plastic dish nasal dermatitis
Vitaligo causes black pigment in the nose and sometimes the lips to fade to brown.
Snow nose causes the nose to fade to brown in winter; normal color returns as summer approaches. Snow nose occurs mainly in white-coated breeds; the color change can become permanent in older dogs. It is not associated with disease.
Plastic dish dermatitis can occur if the dog eats or drinks out of plastic or rubber bowls. It is triggered by a reaction to an antioxidant found in the dishes.