I've read about it many times here on FT, but the whole idea of having any discussion of MQM with GA's has always seemed to me to be a pointless exercise because 1) they likely have little understanding of MQM; and 2) they have no authority to grant MQM. When I've been rerouted I've never worried about discussing it with the GA and always have received original routing credit on Delta, when it was greater than what I actually received from Delta, after the fact. In this case since what was received after the fact is already greater than original routing credit, I'm not sure what else there would be to do anyway ...