Stupid Things I've done on a scot

I was sailing in the Gulf of Mexico two weeks ago and have a little story to share:

After getting the kids to help with rigging and explaining how important it was to make sure that all lines were neat and gear stowed, I neglected to fully pin one of the shrouds. I'm still not sure what happened but it was certainly my fault as I was the last one to touch it. After 3 hours of delightful sailing, we headed in via the intercoastal waterway. On one tack my (non-sailor) wife looked at the leeward shroud and asked "should that be so loose?". I immediately gave her a screw that had been floating around the boat (part of the clean up that wasn't finished) and jammed it in the plate. We dropped sails and motored in for about 20 minutes till we reached the dock safe and sound.

Happy things:
1) No one was hurt and the mast stayed up where it belongs.
2) I had just added the motor mount and mid-boom sheeting the week before. As a result, I had a motor.
3) No one really understands what 'could have happened'.
4) lesson: Check, check twice and check again.