Lots of air when getting gas

Ok so since I’ve owner my 97 xk8, every time I go to get gas I get a rush of air blowing out as soon as I start to take off the cap. If I go slow, it bleeds down, but if I go fast it really goes PHHHEEEEEWWWWWWWWW! Has anyone had this? I would think there may be a problem with my vent, but not really sure where to start