Keep in mind that there are flight reductions nationwide in the next few weeks because of effects of the government shutdown on the FAA staffing.

So it could be that people who wanted to book other flights in upper class cabins booked the flights you were looking at instead, because they were still available/

Or it could be that the airline is pricing those cabins higher because there are fewer total seats available on those or similar routes, compared to last year, not just on that particular flight.

So all sorts of things about flight bookings could change in the next month or so because of those.