Ah, you definitely shouldn’t have gone from : to full in one night of sleep.
I’ve heard other people give similar reports of still healing very fast, but it was usually a result of them using various healing items on that body part.
In my game, I heal pretty dang slow unless I use bandages and such – it takes me two or three days at the fastest to heal to full from about half limb health.
Checking the settings, it’s still at the slow heal rate and has not been increased – I don’t know why you would be healing so fast.