Hello !
Maybe Gnomes are the culprits (mines are well behaved and won't do such a thing).
I think you have a gasket which is as dry as a bone and it has collapsed somewhat, turning the screws loose.
If I were you, I buy a new gasket for the oil pan, and at next oil change, remove it, clean the inside, clean the oil pump intake filter and re-assemble with the new gasket. And you're done for the next 30 years.
There has been report of stripped threads in this area, so stick with the torque tightening figure... Would be bad to loose all that fresh oil on the road, wouldn't it ?