jconway607
JohnWC
I have several aftermarket magnetic engine oil plugs that have a 15 mm or 17mm male hex instead of the 8mm female Allen hex for tightening/removal. So it is conceivable that a brick might damage the plug in such a way as to allow it to fall out. This is apparently what happened here.
Yes, that could explain it. I forgot about the magnetic style drain plugs. Thanks, Paul.