It is thinly possible there was some sort of mechanical issue with the truck...

Yea, the mechanical issue was the driver.
If there was a real mechanical issue with the truck, you would red flag the truck as dangerous and bring it back in or call for a tow if it was that bad that it couldn't be driven back in.
If the truck will not lock into park, the truck is dangerous!!!!!!! and it goes to the shop for repair and not be on the road.
