The take-home lesson for me is to do an EXTRA special preflight after any maintenance. And I'm the guy with the reputation for grounding aeroplanes, just by LOOKING at them. Guess I look too hard for some folks taste, but not my own.
And a few years ago, I became the owner of an orange-handle Snap-On ratcheting screwdriver, which has been the most-used tool in my bag ever since. Dagnabbit EXTRA special preflight....

The likely previous owner has seen it in my hands many times and hasn't said a word. One of TWO snappy tools I own....
Thanks. cubscout