Does she indicate she doesn't want to be there, or wants to be home with you? I mean, separately from saying she likes school and likes the teacher and classmates. One can like the school and the other people and still want to be home.
"She did really good the first couple days and then it all went down hill."
"She has really really good days and then goes back to being bad."
Is someone bothering her, someone or something she's not telling you about. based on the excerpts from above that might seem like a possibility. Maybe she's frustrated because she's bored and is not being challenged enough, while she was at home with you what kind of stuff were you all doing, is she more prepared than others in her class, what they are learning did you guys already cover at home, it might be possible on those bad days, the curriculum was just getting on her nerves because she is so bored, and doesn't know how to express it, or she could be looking around for you because she is ready to go, and she can't leave, so she gets frustrated and cranky, it wouldn't be the first time adults misconstrued bad behavior for frustration. Like when a child is so tired but can't go to sleep, or is sick, they hit (not on purpose,) pull at their clothes, cry, the whole bit.
Long story short something or someone is bothering baby girl.
If you can (you or someone you trust) take a day or two or three, maybe not in succession but stay, watch, don't let her know you're there though, don't let any of them really know, keep as qt as possible, leave like normal, but then come back and observe. If the same behavior doesn't occur, then most likely there is an irritant, if it does occur then you'll be able to really see. Also does the daycare have cameras, then they can pinpoint the exact time of the incidents.
First off let me say that I more than agree with the comments by itsmorethanyouthink. I taught head start for 8 years, until I resigned this past November to stay home with my youngest son. Behavior is learned first and foremost. I wish that you would of given examples of her bad behavior, because often behavior changes start with the teachers. I've seen it all to often, and it used to make me very upset. I was a lead teacher at my school. Anyways my first question is with switching her into a new room did that help her behavior because she's now getting more instructions through out the day. Also did the other room she was in follow strictly by the schedule? Then my biggest thing I personally always asked was what where the other children doing when it happened? Because any good teacher will say monkey see, monkey do. So if the behavior was so out of character for her, and you've never done it at home then it's possible to assume she seen it some where. Always ask questions? Find out what was going on in the classroom when it happened. Then find out what the expectations are of that classroom and teacher. What skills are they expecting her to know to do, and are they showing her first, helping her one on one secondly, and placing in small groups lastly. I've seen it before and teacher put new toys/skill projects in front of children expecting them to complete it right. Then the teacher gets upset either because they made a huge mess, cut something they shouldn't have, or destroyed something. There are a lot of children who enter into school that have no idea how to play. Play is a child's work. You cannot expect her to go into a classroom knowing how to use toys that she has never seen before correctly. Wouldn't you get frustrated as an adult if that happened? Also they should not be sitting all day. I know as parents you want to see those work sheets because it's proof they are learning., but children shouldn't be sitting at 4 doing work sheets all day. Please take a look at the classroom environment, and see what is truly going on. Then before getting upset talk to her more. Let me tell you from personal experience a 4 year old can tell you everything going on in that room, and don't think for a second that she won't tell them everything going on at home. Just listen to what she says, and ask questions to get a full picture. I hope this helps.