Just got a phone call from my wife and she reports that there is a odd issue with my fuel gage. She left work and went to the local gas station for a drink and when she shut off the car, the gage pegged all the way up and WAY past the full mark. I asked her to turn on the key to see what happens and she said it returned back to it's normal reading. Asked her to shut off the key and the needle once again shot all the way up. Typically when you shut off the car, it just stays where it was. Does anyone have any idea of what may cause this and is it something I should immediately worry about? Thanks in advance.