Well the exact same thing happen to me last year when I had my rear tire change at the dealership. it happen after i drove for 500 km, and it was obvious that the pad was not clip into position properly. I was just lucky that when it happen, i was close to home and when the rear wheel jam, I was going 70kmh but on a straight stretch of road. I did fix it myself and did called the dealer after and guess how it ended, wasn't threre fault according to them. I drive a 08 FLSTC. took picture of it that I attach.