I also am confused at why this is titled, "Lie Flat Seats".
But yeah, I'd be ****ed off and disgusted also. Maybe enough to write an ops report on the screwup by whomever forgot to ticket this when they should have. However, I do agree with the others who said this could have happened before or after the new contract.
For the next time, I think I'd call up crew schedule, tell them what the flight options are (that are legal, and in first class), and make it easy for them to rebuild the pairing in my favor. You never know, it might work. I would also check that they issued me a ticket, as soon as I realize that I'm going as scheduled, because I hear this kind of thing sometimes happens. Coach middle seats truly suck. Hopefully you had some beverage service that made it more tolerable.