Sometimes the dispensing of upgrades is just plain mysterious. My partner and I were flying on a very full US Airways plane from Washington National to Nashville last Christmas. Neither of us has any premier status with US. About 10 minutes before boarding, the gate agent called my name, asked for our boarding passes, and without a word she tore them up and handed me 1st class boarding passes. I started to ask why, and she made it clear I shouldn't ask. Wish I could figure it out so I could do it again.