How old were these pads & what mileage had they done.
On a 2011 RT, the inner (nearest the wheel) brake pad back plate has two holes in it, if the disc is visible, they are at their wear limit.
The inner pad friction material is also thinner than the outside pad.
Is it possible that moisture has got between the back plate & the pad and that it's the formation of rust which has forced the friction material off the back plate.
http://www.bmw-motorrad-store.co.uk/bmw ... odels.html
Click on the 3 images in this link to enlarge the photos & all will be revealed.