Just got in from a little 60mi cruise and was gonna spray all the nite insects off when i hear a noise. Sounds like a tapping coming from the passenger side up underneath where the cats are. I rev the engine just a hair and the tapping speeds up then slows down with the RPMs. I turned the engine off...sprayed the truck off (15mins) and started it back up to go home. Tapping still there. Any ideas? Am I in danger?