Sounds like an EVAP issue - can be normal. I would double check that your gas cap is on tight (until it clicks) and make sure that you do not overfill the tank (adding extra clicks after the pump shuts off automatically). But may be also a sign that one of the hoses or valves are leaking gas fumes. If you get a check engine light - that would confirm a leak or fault in the system. might also be the fuel pump issue that seems to plague some of the 2005 models.