Yes! It seems to have started today (Oct 18). I did a transfer yesterday bank to bank with no fee. Today I made a transfer and there was a US$6.00 fee! (I cancelled it.)
I tested a new transfer with various amounts and it seems to always be 6%.
This changes the very nice rate of 193.30 pesos to the dollar to 181.70 pesos to the dollar!!!
Back to the dollar blue, cash and cuevas. (Maybe, depending on how the rates evolve.)
Time for a boycott of Western Union.