I just booked my first B-class tickets (H on the outbound, B on the return) - I usually book lowball K, T, or V class fares - but this was a for a biz trip to SLC next week & NW's B-class $860 beat out DL's $950 & UA's $1100 (though it didn't beat out AA's $770, but I don't fly them) flights for the tickets (spring break in a ski town??).

I'm flying DCA-MSP-SLC-MSP-DCA. The SLC-MSP is NW coded, DL operated & the MSP is NW coded/operated - both flights are booked into NW B-class. I noticed that even though my retun is still about 11 days away, tonight, the MSP-DCA has been changed to a first class seat booked into P-class. My SLC-MSP ticket (which is an NW coded B-fare basis) is still in coach.

Will SLC-MSP on DL get upgraded automatically into an F-class seat due to the fare? This wasn't a fare that on NWA.com showed as B-up fare where it automatically books you into P - it was a normal B fare that didn't appear to book into P. Mistake or is that how its supposed to be? I normally don't buy this high of a fare basis.

Thanks!