It’s exactly that. YM controls the pricing on it just like any other seat. Before I retired from AS they actually had a dedicated group that focused on just PC, as the yield from those seats is almost pure profit and the stated goal was to maneuver pricing to ensure that it maximizes $. I’ve been gone about 3 years now, but through the employee portal, they say they still have a robust program to squeeze every penny from that class. As flights get busier, they’ve gone to offering PC with open center seats, it restricts an already small supply and allows them to raise the premium they can drive by offering a bit more comfort/distance from your neighbor. Like anything an airline offers, when you see a price that works for you, grab it. Because before departure they’ll find a way to get whatever they can for that product/service and lately that means it’ll cost more day of departure.