The thing is that it's hard to come up with a scenario that he could have done just by retorquing lug bolts. At 150K there are plenty of steering and suspension components that can need attention, and maybe the timing is a coincidence.
I think you're going to need to get it on an alignment rack and locate the source(s) of the problem. Swapping hubs and lug bolts pre-emptively is not cheap (or easy, if you're talking about the rears).

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Prost!