we had an old Case tractor that was riding kind of rough and I couldn't figure out what the problem was until I watched it from behind. 3 of the four lug nuts on the left rear tire were completely gone and the other was about ready to go. It was flopping all over the place! I found it to be quite humorous.

Anyways, if I were you, I'd be doing some major bitching... That's totally unacceptable and downright dangerous. If I didn't know any better I'd think that you were serviced by a former Toyota employee :O

Lol.............hahahahahahahahahaha.............. .roflmao

Yeah it possible for them to loosen, but after doin other jobs, you should be able to tell whether the wheel is on flush or not when mounted and tightened. It is still human error, but with the possibility of a faulty lug nut or stud. I now see shops will have a another employee come check torque as a security check. Thats more comforting then being in a hurry.