I dropped mine from my hand onto a hard tile floor. Since I was walking briskly at the time, it slid away from me on the floor at quite a high rate of speed. It somehow managed to slide on the exact trajectory to hit a 3 inch by 8 inch opening in the floor that it then slid through, falling 12 feet straight down to another hard tile floor below. I shat myself and ran downstairs to find the phone still working perfectly, but with the tiniest quarter-inch scratch in one part of the chrome. I'm not at all worried about babying my iPhone anymore.

So, I think your problem is pure unlucky coincidence, or else you had something loose already and the short fall just finally made the problem manifest.