Tinkerbell has long hair when she is "born". When she gets to her house she has shorter hair! Like from past her shoulders to above them. The only thing that happens between those two times is 1. She flies. and 2. She tours Pixie Hollow. You can catch it when she is fixing her dress-thing (if you could even call it that). Make sure you see it then because for the rest of the movie, her hair is in a tight bun.