A few times this year, I was upgraded on one segment and not the other (ie: MSP-GRR Upgraded, SEA-MSP not upgraded) I will check the fare bucks and see where F is. If it is at 0, then I will check again late that night or first thing in the morning. When I have done this, there has always been seats added to F. I then call NW and ask to be upgraded. You could wait until that evening for the automaic upgrades, but I don't like taking the chance.