Proud owner of a 2012 WRX (purchased new, 9k miles now) here with an issue I haven't been able to figure out. I was starting on an incline and stalled out in first. When I stalled, I heard a muted ping sound, and then I started hearing a squealing scratching sound in first and second that did not seem tied to acceleration. In reverse, the sound was much worse-- more of a loud metal on metal grind. I carefully drove the one mile home and took it to the dealer the next day. I then got a call saying they could not reproduce the sound. I then took it around the lot and around the block a few times, and sure enough the sound was gone. I'm having trouble coming up with a good hypothesis. Maybe I chipped a tooth on a gear, but this issue has had no perceivable effect on the way the car drives. Any ideas?
To clarify -- the noise in reverse I'm describing is not the normal whirring you get from a straight-cut gear