My son had a mole on his neck which he used to pick at when he was little and often took it right off. It always came back looking exactly the same. Eventually he had it removed because it rubbed under his shirt collar and the surgical procedure to remove a mole also means taking quite a lot of flesh from around and under it as well and several stiches. It was a perfectly benign mole, as most are, and yours will mostprobably be absolutely fine. However, if a mole changes without interference it must be investigated. Personally, I would seek medical advice, especially as it is just hanging there!