MSPeconomist

Since the difference is $10, could it be that the new peak summer days surcharge of $10 (most days June through August) announced on most/all legacy carriers only shows late in the booking process? I don't remember how the holiday surcharges were handled when they were introduced at the end of last year.

Or does the fare code change when the price changes, which would seem to indicate a last seat availability issue? In that case, purchase the tickets one-by-one as suggested above unless children are traveling or you otherwise need to be on the same PNR.