UA many years ago used to do the same for *G members on check in, so did US when they were still part of *A. AA still does it for OW Sapphire (actually Ruby as well on check in, though Sapphire is in advance), so it's not unheard of.

I wasn't even award that TP had a Premium Economy section since they don't fly any routes I'd typically use, but good info to know.