Thanks for the support...or lack there of.
The motor was not open for any length of time....only when working on it.
Nothing was dropped in there, as far as I know. No missing parts, clips, etc. Everything is accounted for.
There was coolant in bike. heat cycled, as as I did on the other rebuilds. Only other thing than the previous, those were done in heat of summer, and this was during colder, more recent weather.
Basically, I did nothing different than I did on previous top end rebuilds. Makes it that much more baffling.