Nope, the track still comes out of Clermont in Ohio.
The most common answer you'll get to "what changed with B&M?" is the tolerances of the trains. Whether that's true or not, or even the main cause, who knows.
I don't think I've seen anyone pitch the idea- but I would raise the possibility that the supplier of the
rails changed in the last few years. It blew my mind when I learned this, but in
this interview here from Clermont, the worker says the
RAILS are "European-grade German steel, that are rolled (bent into shape) in Italy", THEN shipped over to Clermont and welded to the rest of track at assembly.
If they were looking for costs to cut in the whole manufacturing process, that seems like a pretty large one. I don't have evidence to support that, but seems like a reasonable possibility.