I saw something similar a few years ago when we were going EWR-NRT. At some point there was a glitch with the seating chart and all of the Y+ seats turned to Y-, and all of the J seats turned to domestic F seats (the orange angled oval seats turned to orange squares). Obviously since you are flying on a domestic AC, you wouldn't see the J's turn to F's. I did a phantom booking to see if I could have gotten a Y+ seat for the Y- price and it did allow it. In hindsight I should have seen if the F (J) seats were cheaper.