Surprisingly enough, drinking and eating out of plastic bowls can cause the pigment of a dog's nose to change because a chemical found in the plastic interferes with the dog's ability to produce melanin. There are a few other conditions that can cause nose pigmentation to lighten, so, like Zoey's Mom said, the color of the nose may constantly change.
Chip prefers paper plates too, but he drinks out of a plastic water bowl (one of the automatic water things...I don't think they sell them in metal).Really, I didn't know that. As I mentioned, I learn something new all the time. Zoey eats off small paper plates as she does not like to eat out of the bowel but her water is in a metal bowel.