I'd like to preface this by saying that I am new to chickens. I went out to check on our 4 week old chicks tonight after work and noticed that one looked like she was pasting up... I freaked out and ran to get the DH who I insisted take care of the problem right away. He picked up Nugget, our black Australorp, flipped her over and started laughing. The "pasting up" was her black butt feathers coming in. I feel pretty silly now.