Gas Pedal Rattle at Low RPM

I just bought my first car. All in all everything seems to run great, I had a mechanic look over it and he found no leaks or anything really wrong with it. However, I’m now a few days in to owning the car, and I’m starting to notice something a little strange.

When driving at low RPMs, or coasting after accelerating, I can feel a a rattle through the gas pedal. I can slightly hear the rattle too. It’s not exactly rhythmic, and it could perhaps be described as a clunk because of that.

The car is a 2002 Mazda 626 with 96k miles on it. Any ideas?