Ok so my white one (mist) has always had a dirty nose look, with the brown splotch on her nose. But lately it get's darker, now it's almost dark grey. It actually looks like she has a dirty nose, but I can't think of what it could possibly be. It's so odd.
You can't really see that picture clearly. I'm not sure if it is anything serious, so I think you might want to wait for someone else on here who knows. Or you could simply take Mist to the vet for a checkup.
I never knew what my oldest girl was until now. She's also a PEW, but a few months after I got her the fur at her nose turned light brown. It also darkened slightly in a ring around the base of her tail. (No, it's not just dirty.)
pooky, is your rat the one in the avatar? i think it's a blue, but there are different shades. i'm still trying to figure them out. here's a picture of scout; does anyone know what "type" of blue she is? lol, just a plain old blue? and what about pooky's?