They have always been rock steady.
I see now, that that can change.
How it did, is a complete and utter mystery to me.
I fully understand. From a consequence standpoint, knowing that you will be trying to kill an animal in a manner where you don't wish to cause it suffering, then it should be proper practice to verify your gear before attempting to make a kill.
It is sort of like having your reliable car checked out by the mechanic before making a cross country road trip.
I referenced folks with issues above concerning sighting, hunting, and problems. Here it is.