Its really not that unusual. Starting school represents a change. Home is typically a lot nicer. As margypops said, do talk with her teacher. If she has been teaching awhile, she will have lots of experience with this behavior. She will be able to tell you what to do. And many times, the talk with the teacher will also cause the teacher to show a bit more attention to the child.
Perhaps have a word with her teacher .they will be a reason she has suddenly started this ,does she have any friends at school, what does she say when you ask why she doesnt want to go.The fact she also says she wants to come home early maybe that she wants to leave before home time , check out any happenings when you collect her from school.