Unless the pile actually froze, it wouldn’t stop cooking, the microbes will still be in there working away.
If it was in cool temperatures and just in a pile, it may have just been releasing heat nearly as fast as the microbes made it.
When I mix soil, it’s inside and in big (500L or 1000L) bins, being contained like that, it generates a lot of heat. This is good for killing off errant seed that may have good in the mix but not necessary.
If i we’re making soil for raised beds outside, I would do it in the fall and it would cook all winter but wouldn’t generate noticeable heat.
As long as it is not hot to the touch, and this long after you mixed it, it will be fine for you plants