If it's both seats, then I bet you have this factory option:
XSU Lowered seats (-10mm)
I have that option on my car, and the seat bottoms look a lot like that. So, it's a "feature", not a "problem"! What they actually do is shave down the foam as they build the seats. Whether it's for taller drivers, or drivers wanting to lower their COG that extra bit, I dunno. The previous owner of my car was a national autocross competitor.
