Last night one of my hens was sleeping in a nesting box. I didn't think much of it, since they all prefer the same box and often line up to use it during the day. I have seen other hens do this as well. This morning she came out when I opened the coop and she had already laid an egg, so I brought it in. Later today, she was back in the box and has since not budged, and is squawking at us if we go near. If she is sitting on any eggs right now, I know they are not hers and I'm not even sure they are fertile. My other problem is we are leaving on vacation for the next 10 days on Tuesday and a friend will be taking care of my chickens. I've told her about the situation but should I be very concerned about her? Thanks for any advice! This is my first year with chickens!