Just got back from my first oil change at 996 miles. I told them about my pinging sound, and that I wanted them to diagnose it. They told me that they found a loose exhaust clamp and tightened it down. They told me they then started it up and listened for the pinging. They could hear it on the lift. (As luck would have it, it was doing it today) I was told it's coming from the catalytic converter, and that many of them make that sound and it generally gets better over time. I was told that if it gets worse, or there is no improvement at all within 5 - 6k miles, to bring it back and they'll look for another possible cause, but they're 99% certain it's the cat...
Also, the passenger seatbelt locks REALLY easily. I asked them to look at it. They agree that it locks too easily and ordered a new one for me.