Great explanation, however why do I never see "Your fare has increased $55" on sites like Expedia but sites like CheapAir.com have it all the time. I expect Expedia and CheapAir.com have the same source of data therefore it does seem like a bait and switch situation.
Expedia may decide to eat the difference (it can go up and down) and other folks may not be able to afford this (remember that airlines only give like $10 per ticket, not much margin).
