Memory test failure, fix and some questions

Overnight my B590 developed a memory fault.

On boot up, a single long beep, and the machine would drop into the bios. Upon running the inbuilt memory diagnostics, I found that values being written during the test were coming back with a single bit always set to 1.

Did usual reseating of the DIMM, changed the DIMM location, swapped the DIMM with a new module. Same error, indicating that this was probably a motherboard issue.

Ran memtest86 (4 passes) from a USB drive with no errors. On rebooting, Windows started up as usual.

Q1: Why did this work? I can only speculate the memtest somehow cleared the stuck bit on the motherboard. Bad capacitor?

Q2: Is this problem likely to resurface?