My parakeet laying all the way on her belly by: Linda
This is NOT normal though I cannot say what it may be that's going on. Could be she does have some kind of pain there, and this action helps it to feel better.
Your bird needs yearly thorough exams with an Avian Vet. So if you have not taken her in yet this year, now is the time to have vet examine her and see if they find anything wrong. As I said, this is not normal behavior and points to something not being right with her.