My male tuxedo cat does exactly the same thing. I asked the vet because he seemed to have really flaky skin when I would scratch or brush him. She said it is probably dry skin and to use baby lotion on him. I have taken the baby lotion and massaged it in as much as I can. It seems to help him, but he still gets twitchy. It is much worse during the winter than it is during the summer. It's hard not to mess with him because he looks so funny, but it seems kinda mean to mess with him.. HAHA
Yeah...it sounds normal to me. If this is a sudden, new obsessive behavior though...I'd consider the possibility she's stressed over something. As long as she isn't removing fur to the skin, I wouldn't worry.
This is normal behavior, in my experience.