You hear about this now and then. If you think of all the touring bikes with the HD set up, very rare % of chance this will happen. Then remove the % of them that were improperly installed, and there is even more little chance of this happening IMO. I am not saying it does not happen (because it does)or anyone this has happened to hooked them up wrong, all I am saying is I am not bolting on and losing the convenience of removal due to this rare event. Now I suppose I will lose a bag on my next ride!
Still, I am sorry about your bag. Hope you find one soon.