I have never had that happen. Recoil wouldn't do it, I wouldnt think unless they loosen up and then the scople bases might shear off the screw. Maybe bumping something with the scope. A fall perhaps. Crushing in the car.

Hey, pick up and move on. take a drill press, drill out the old. Get you some quality Leupold bases and rings. Clean out the old oil in the holes and use lock tight blue on all screws. Never have it happen again.