I have 15 1 week old chicks. They are acting and functioning in a completely normal way except for the fact that about 10 of them are puffing out their feathers/wings, when they sit and sleep on the roost under the heat lamp. Why? Should I be concerned? The thermometer says 90 degrees. The roost is underneath, might put them a bit closer to the heat lamp. Should I get rid of that roost? They seem to be acting normally otherwise. I use medicated chick feed and vitamins in their water. They have been healthy and active up to this point. Thanks.