My 19 chicks are almost 4 weeks old. I moved them to a 4x8 brooder this morning and they loved it all day. I noticed as the sun was going down, they started making unhappy chirps. Thinking they were stressed I moved them back to there old brooder. They just piled into the corner pushing making unhappy chirps. They just got quiet, but they are still piled into the corner. What did I do wrong?