happened to me twice. i read somewhere that if you did the upgrade a day prior you would get the new MQMs. however, it is not the case. i called delta twice and they both said unless you call AF/KL/DL to change your class of service (meaning paying the fare difference), upgrading that online would only earn you the original booking class. i have learned from that and will never not pay for upgrade for that one hour intra-europe flight.