My hens have an automatic door that opens/closes from a light sensor. Like clockwork, since they have been in this coop ( since May), they have gone in before the door shuts the final time ( it opens once more for stragglers). We just got a very cold snow storm and last night after dusk and the door had shut, one of the birds was perching under the coop on a crossbar and tonight two different birds were perching on a crossbar with the other two hens safe inside. I have a flock of 4 that are very close. Any idea what is going on?