My hen, Rosemary, for past couple of months or so has had very pale legs (They are supposed to be bright yellow). She also seems thinner or smaller than she used to. My younger pullets who are 22 weeks old have the bright yellow legs and are as big if not slightly larger than she is. They are all Dominiques. She is continuing to lay regularly and her comb is still red.....and is otherwise acting normally. Does this happen as they age? She is almost a year and a half old. What could this be?