Annoying thumping

[FrostFire]

I didn't really see a "troubleshooting" kind of forum here, and with my issue, I figured this would be the best place to ask. I just bought a Fender Jaguar bass and I play with a Fender Rumbler 15 combo amp. The thing is, when I tap the string with my finger as If I'm going to pluck it, it makes a very audible thump from my amp. Keep in mind, I'm not slapping or popping, or tapping the string on the fretboard. I'm just kind of setting my finger on the string. It might be the way I pluck, but I'm not sure. Anybody know why this might be happening?

[darthplagis]

do you have the bass boosted? (the bass side control plate, wheel towards bridge)

other than that all i can think of is a bad connection to the battery with you being a ground and completing the circuit. (battery - wire connected to bridge grnd)