I found one of my pullets dead this morning. She was about 8 months old. She laid an egg that day. I really didn't see them much during the day because I was at work but everyone came out in the morning and seemed fine. At night when I shut up in the coop she was laying in the run. I picked her up and put her in the coop and she seemed unsteady on her feet. She laid down in the shavings and feel asleep. I thought she was just really tired and figured I wouldn't bother her. It was pretty cold last night but it has been the last few days and they've been through a lot worse. No signs of injury. Any thoughts on how she died? Should I be concerned for the rest of the flock? Everyone looks fine today.