Nose color?

I have a question....

My cat Lily has an (adorable) pink nose. But every so often we'll notice that it's just not as pink as it normally is. Does anyone know why this might be? DH thinks that maybe she's just cold, but she shouldn't be that cold as our house is about 68 degrees.

Sunshine's pink nose gets paler when he is cold or not feeling well. I've never noticed any of my other cats having this sort of thing.

QT's pink nose is more reddish when she is extremely active, paler when she's napping. It's also whiter when she isn't feeling well.Of course, the difference is very slight. It isn't like a strobe light.