Recently I have noticed that two of my hens face and comb look like they are covered with a chalky, white powder. It's not raised or anything. It just looks kinda like dry, chapped skin... Almost like they've been playing in flour. They are otherwise perfectly healthy and normal. Is there something wrong with them? It's been chilly here, but nothing extreme. They have a warm and comfortable coop and are eating/pooping fine. Thanks in advance for any insight. *Also wanted to add that this hen has never had a "true red" comb. It's always been a darker reddish-brown color.