Stop in for a cup of coffee

I’m stumped.
How could i have left wheel bearing hub bolts loose? As in one fell out and wedged the back wheel. I have done hundreds and hundreds.
Im lucky it was a good customer,and i owned the failure 100%.
So, replaced bolt, loctite and torqued up all the bolts.did both bearings,so i took other side apart and rechecked my work, adding loctite there as well.
That, im sure will never happen again. Im thinking hub wasnt properly seated when i tightened it.
Mistakes happen. No one is perfect