Odd, you might want to check if your slicer has any of the fancy hole compensations turned on.
No neither should be an issue. You can use a drop of loctite or glue in the holes. I am really starting to like loctite for loose holes. It takes a while to dry but I like that it tends to be a but more hold than even superglue.
The nut screws really do not even need to be tight, gravity does all the work.
This is good news, but I will invest in some loctite nevertheless.
All other holes where okay. I use the Creality Slicer 4.2.1 based on Cura. I will have a look at the settings, but it is totally possible that the flow at the end of the print was just not optimal anymore.
I had the same problem in both places…maybe a calibration issue with my 3D printer, though tests say it is dialed in. My fix was to use a bit of thick CA glue and spread it on the sides of each hole with a toothpick. I did two rounds waiting for the glue to be fully cured between rounds, then self tapped the screws.