In her version of the tale, Ms. Duncan never told Clare her dancing was inappropriate. The issue had always been about the dress. Clare insists that Ms. Duncan objected to her dancing, and was determined to kick her out from the moment she turned up.
Because there were other girls there in equally short dresses, Clare feels like she was singled out. As a taller girl, she also points out that other girls whose dresses were shorter got away with it because of their height.