XMP - system post in safe mode. Happened once.

Hi. Its my new topic in short time. My mobo is Asus Z370 Pro Gaming. And rams: Gskill 2x8GB 2133mhz ( XMP 3000mhz ).
Cpu 8700K. When i choose in UEFI first time XMP profile i saved and booted fine to UEFI.
I turn off pc,turn on again after 2 hours, and then, i met screen:
THE SYSTEM HAS POSTED IN SAFE MODE.
This happened just once. Now its booting fine,but i dont know why it booted just once with this message.

This is screen from internet ,but the same msg:


My psu also is Corsair 750RM i

I tried to reproduce this warning but i am not able to do that.
Reverting to standard and then again to XMP save. Turn off pc. But not warning.
Any ideas why it happened just once,and still its something wrong?

Memtest not showing errors.

 

I have a Z270 Prime A, I had a AIO pump failure/overtemp shutdown which led to me virtually re installing everything on my PC, I had an issue that sounded like yours, and I had the XMP switch on and the new BIOS setting was off, once I set the BIOS to match the switch on the MB it booted fine. Not sure if it's the same thing though.