I can't figure out if there is any rhyme or reason to it. I booked a ticket for summer travel a few weeks ago and have watched the fare class change and price go up and down multiple times.
Also was looking to book NYC to LAX last night. Found an itinerary I liked. Went back to book it this morning and the price went up $100. LOL. I'm just going to wait as it will probably go back down in a day or two.