i did want to add that i would NEVER mention the word "evaluation" in passing, and I personally feel that a teacher should save that for an actual meeting. It would have been more appropriate for her to say that she would like to meet with you to discuss your daughter's progress.
most preschool teachers would not suggest an evaluation simply because a child does not stay in her seat. while we would LOVE it if all the children could do that, it is certainly not expected that all of the children would. If we truly expected that, then more than half of the class would be evaluated. I suspect that she may be seeing other signs that warrant investigating. i cannot even begin to list "normal behavior" in a three year old, because there is a very broad spectrum that is considered to be normal. I would suggest you go ahead and have the meeting and hear what the teacher has to say. Some children behave very differently at home than at school. Some cannot handle the structure (or lack of depending on the program). Others cannot handle the social situations, or all of the stimulation that a classroom environment provides. Based on "she has trouble staying in her seat and just goes off and does her own thing," it sounds as though she may have difficulty either processing or accepting directions. This can be normal or abnormal given the child, age, situation, etc... When you meet, be sure to ask what is expected of the children. A 3 year old cannot be expected to sit and do work. Sitting activities should not last more than 10 minutes or so.
Meet with the teacher, listen to her, and ask questions. Be sure to take notes, because i suspect you may be overwhelmed. Once you have specific examples, feel free to come back and ask if it is typical behavior for a three year old. Good luck!