i just got back from a drive in my 68'coronet, i stopped in my driveway and laid the car on the floor and spun down my driveway i hit the brakes hard then drove into my garage, i noticed a small gas spot on the concrete right under where the vent tubes are on my gas tank, i am guessing when i hit my brakes hard and forced all the gas to the front of the tank caused this, is this normal? or is something wrong with my gas line vent tube?