Maybe the bolt was not closed completely when the safety was engaged and when the bolt was manipulated to clear the safety was moved forward resulting in a safety off. The trigger will be able to be manipulated floppily if coils have been removed and the safety lever in the mid position will sometimes act as the trigger. The detent in the bolt will not allow full travel of the trigger until fully closed and you can get the safety in between its arc of travel easily. Try it a few times, you'll see what I mean. If my words do not describe completely maybe someone else that has seen this before will jump in. The condition escaped engineering until production was started and has been discussed before. It could be why there has been no obvious signs of defects and the rifle performed satisfactorily afterwards.