Sorry this is a short answer but I'm pushed for time right now for a long one. My question would be if you were away for 20 minutes - What were the teachers/staff doing? I would expect that it would be part of their job if not personality/nature to encourage children to play - certainly ones who need a little encouragement. She may just be a child who likes to be along - maybe its just all too much for her with new choices and making decisions. Have you tried asking one of the other family's round for coffee and letting the children play - you can then see what she is like on a one to one basis - maybe its just the busy environment of school which is getting to her.
Good Luck - remember she probably will not be shy when she hits the teen years!
