1999 Prelude - Bumped a Driveway

I was driving out of a friends driveway and bumped the underside of my car pretty good on the passengers side, in the front/very front of the car. Ever since, it's made a rattling/vibrating noise between 2400-2600RPM's, though it might do it more (I just can't hear it from inside the car, not even with the windows open, radio off, and A/C off).

I know that the catalytic converter is in that general vicinity of the car, and also know that it's kind of expensive to replace.

Is there anything else that might be causing this rattling/vibrating? I've checked the underside of the car and nothing is hanging down - I've also not noticed ANY performace impact - I still get the same amount of mileage per gallon of gas and the car drives exactly the same.

Thanks!