Camaro_or_TA

Hey guys, decided to get in the Camaro and run it at the strip, fast forward.. so I powerbrake first, burn um for about 7-8 seconds. Run down the track, everything's peechy.. so I'm getting on the brake, put it in first gear to go around the turn to return to the car lot and I hear this odd sound, it's like a very faint rattling sound, but it's very fast, but it sounds like garbage, I could only hear it for a fraction of a second then it goes away, and it only happened in the beginning of every gear it did it in 3rd, and 4th gear maybe 5 minutes after that, then all of the sudden it just stopped making the sound and it would only make it seldomly like maybe once or twice a day. I don't really feel any powerloss, I'm thinking that it may be the transmission mounts but it could always be something else. I beat on the car pretty hard that night but it's bone damn stock so whats the deal with this noise? Now the car very rarely makes the noise unless I'm at like 45 MPH in 6th gear and push more then 50% throttle. I don't want to have to take it to GM and get everything looked at if it's not even that big of a deal, the car is an 01 Camaro SS with about 30k miles, thanks for any help guys.

Asmodeus

look around the exhaust system. noises that happen at very definate rpm's are usually found around the exhaust and cats.