We started out with 9 black-sex link chicks (before rehoming some of them) and all but one had a normal colored comb. I have one that has a black comb - she is about 12 weeks old now and the comb is still completley black. It is not from frostbite - she was never exposed to cold temperatures. She is normal in other ways - she's the same size as her cagemates. Is this unusual? Will the color of her comb cause problems with her overheating (we live in Phoenix)?