Question on GFI outlet
A few things come to mind.
The GFCI could be bad. They are electronic after all. Some last a dozen years. I've had a couple fail in a dozen weeks.
A wire might be pinched in one of the boxes, and it took until now to part the insulation and short the conductor.
A staple might be overdriven that is securing one of the cables, and it took until now to part the insulation and short the conductor.
If you lack meters and such for some tests, replacing the GFCI isn't a bad place to start.