Filled the tank up this morning and drove from Denver to Pawnee Grasslands. 80 miles? Hiked for a few hours and drove home. Got out of the truck and noticed a gas smell. Unscrewed the cap and lots of pressure came out. Pushed down on the flapper to get all the pressure out and started putting the cap back on. Heard more pressure releasing. Maybe it's coming from the two holes on either side of the fill tube? Waited about 10 minutes, still getting pressure releasing. Let it sit for 15 minutes went back to it. Smelled gas around it. Loosened fill cap. Can hear pressure releasing if I unscrew about one turn. Can't hear anything with the cap removed. Anyone have any idea what's going on? I did noticed a gas smell about a month ago after I filled up and was slowing down at a stop light.