While I don't think much of WM's service center let me throw this out there.
It's entirely possible that someone at WM either failed to properly tighten the lugs or overtightened them; either of which could come back to bite later.
And yes, it may take a week, month, or even months to happen.
It's also possible that someone in the past may have damaged the threads. WM may have installed new tires and properly torqued them down but due to any possible prior thread damage the lugs could have worked loose.
I'm not defending WM here; only pointing out a possibility in which they may not be the ones behind the root cause of the problem.
About 2 years ago my daughter bought new tires (Goodyears) at WM and was visiting a few weeks later. She asked me a question about her car so I went for a ride out the highway. At highway speeds the car was shaking itself to pieces so I suggested back to my house. Since I have a wheel balancer at my house I pulled the 2 rears off and found one tire to be 1.5 ounces out of balance with the other, believe it or not, 4+ ounces out. An ounce and half is a bunch but 4+ is equivalent to a country mile.
Needless to say, in those few short weeks the tire that was 4 out was totally ruined and had a huge flat spot on it. WM balked at first but with "encouragement" from the store manager they replaced both rears again.
For what it's worth as an FYI, WM does not even own their service centers. They're a subcontract operation and used to be operated by Quaker State. Whether QS still runs them I do not know.
Those operations are under a bunch of stress too. Factor in relatively inexperienced employees along with the criteria they work under (the service center has to meet certain percentage goals in regards to net, gross, etc.) and you can see how problems can develop.