I just checked in for my NW flights tomorrow LGA-MEM-IAH which I booked through Delta as an award ticket. The online checkin offered me a $35 upgrade MEM-IAH which I declined because it's only an hour flight so I don't need a $35 snack up front.

When I printed my boarding passes it put "Premium" under my name. What gives me this distinction? I have no status with NWA, in fact I have only flown them once and I didnt even pay for that ticket. The only miles I have from them are when they were partners with Sprint PCS. Any ideas???