I don't know how you handled this. But I would go BALISTIC on the school! I would speak to whoever witnessed the incident. I would speak to whoever sent my child to the office. I would speak to the principal. I would speak to everyone! The teacher said she did not witness the incident and that she was going to speak to the principal. But the teacher is the one that had your daughter call you and tell you that she had "inappropriate behavior"! I would have a few things to say to the teacher also!! If you don't get proper results, you can speak to the superintendent. But I would not let this go without EVERYONE at the school knowing exactly who I was and what I thought about what happened!! Hope your meeting goes well!!
Perhaps you can use the opportunity of this meeting to establish some sensible, level-headed standards. Behaviors such as those that you describe can be dealt with, if intervention is needed at all, with simple limit-setting. They needn't be framed or couched as inapropriate if, by use of the term, is meant to imply some sexualized component to the behavior. It is possible for schools, in a sincere attempt to be responsive to societal concerns, to go overboard and mischaracterize typical childhood behavior.