Before a recent trip to Yorkshire I noticed that the front tyre on my FJ1200 was a bit worn. I decided to swap the wheel with that on my old FJ that had a new tyre on it. When I removed the old bike's wheel one of the front pads fell apart. The pad material had detached from the steel backing plate. Moisture must have got in and caused corrosion forcing it off.
I don't think that the pad would fall out while you were going because there's no gap between the pad & disc but it's a scary thought that I'd been riding about with it like that.