One of the potential weak points on a 1911 pistol is the plunger tube. Shortfalls in either materials or workmanship (usually workmanship) can lead to the plunger tube becoming loose in the frame, or even completely falling out of the frame. The latter tends not to happen, since the grip panel will usually hold it in place.
I recently have seen 3 different pistols suffer failures due to loose plunger tubes. On 2 of them, the strong side thumb safety lever snapped off. The other had the safety detent come out of the tube and bind the thumb safety. In each instance the shooter described having noticed that the operation of the thumb safety had been feeling odd in the period leading up to the failures. Since the grip panel was pretty much holding the tube in place, their cursory looks did not immediately show anything to be wrong and they simply attributed the feeling to normal wear of the safety. (For reference, each pistol was at least above 6k round count.)
Repairing or replacing the plunger tube is a fairly straight forward procedure, provided you have the tools to do so. If you shoot a 1911, especially one with higher mileage, do yourself a favor and give the plunger tube a look when you are doing your normal maintenance.