I would talk about it with you Child Health Nurse.

It doesn't sound too bad if she is turning it both ways some of the time. It is important to find out though, and identify if there is a reason for it, or if it may be an issue.

I took Milo to a cranial osteopath (very gentle, not that it sounds it!) when he was 7 weeks old, for this reason, to check that everything was OK etc. He was doing the same thing, and the muscles were tighter on one side (likely from the birth process, or how he was sitting in the womb - milo was well engaged for at least 2 weeks before birth) and once this was sorted he was fine.

I only had to go twice, and it improved his feeding to boot.

Still, I did notice that with sleeping, he would go a few days always looking one way, and a few looking the other. Even If I put him down with his head in the other direction, it would be back within a couple of minutes.