One of our Ameraucanas has developed a very large 'sweep' (I think that's what it's called--that spot on her back just in front of her tail) in the last two days. It is twice as big as it was a day or so ago--big and standing up high. Some of the other girls have the same prominent feature but not nearly as large as hers. We think that she's the only one of our eight-month old pullets who is not yet laying. That makes me wonder if there's anything wrong with her or if this enlarged sweep might be a sign that she's about to lay. Anyone have any idea what this could be? Thanks.