I buy mostly California and Oregon beef for regular cooks, but, the usual commodity stuff from the restuarant supply for larger cooks. Because I do not use a normal time/temperature process, I have not noticed any difference in my cooks. But, it would not surprise me to hear that some feeders have switched to a different feed, nor would it surprise me to hear that your butcher had to switch to a different supplier.
It is also possible that younger cattle coming to market are a little less likely to finish off in the same way.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."