This just happened (apu2 fail)

[senser]

I love apu2, but this just happened.
I was downloading the new flight simulator when all of a sudden my opnsense apu2 router stopped working. I couldnt ping it so I power cycled the unit. It would not boot again. The LED kept flashing and the board made a repeating click sound...
I thought all is lost, no flight sim for me today...when I gave it another try. About an hourlater I thought "lets plug it in and keep it clicking@...and voila, after like 3 minutes of clicking noises opnsense was booted again.
Now what was that? Anu ideas? Should I be worried and buy a backup board now?