I noticed after a couple bumps and a couple hours of playing with my friends on bass (fender precision deluxe with a PJ passive configuration), that there was a tiny volume coming from the pickups from the amp. I know that I have bumped my bass somewhat, i haven't really done anything extreme, but if you look closely there are a couple problems. anyways, I'm hearing from a friend of mine that if you spend a long time practicing, then on guitar he's noticed that happening (in this case a long time is 3 hours straight). Is this a problem with the bass or the amp. someone help me please.