My buddy brought his, new to him, 04 ST1300 over because he felt the rear brake was dragging and wanted to compare with mine. It had just been serviced at a dealer. I rode his and knew immediately it wasn't normal. He said he could hear scraping sounds but very slightly. I couldn't hear them. I put my hearing aids in and still couldn't hear it. All I could hear was wind noise. We pulled the hard bags off of it and I peered under with a flash light. I saw it right away.
It is quite easy to make this mistake. In the picture, the end of the brake towards the front of the bike has a U-shape. Half of it was inside the caliper. The other half was below which allowed the brake to drag on the rotor and not allow the caliper to release all of the way. He was fortunate that it was on the side that we could see. If the pad had been this way on the other side (left side of the bike, facing forward) one can't see it we'd have been going through the whole system, one step at a time. We simply removed the pin, lifted the pad, ensured the left pad was in place and replaced the pin. All was fine after that.
It is quite easy to make this mistake. In the picture, the end of the brake towards the front of the bike has a U-shape. Half of it was inside the caliper. The other half was below which allowed the brake to drag on the rotor and not allow the caliper to release all of the way. He was fortunate that it was on the side that we could see. If the pad had been this way on the other side (left side of the bike, facing forward) one can't see it we'd have been going through the whole system, one step at a time. We simply removed the pin, lifted the pad, ensured the left pad was in place and replaced the pin. All was fine after that.