I just noticed this as well. I have been keeping my eye on LAX-JFK in September for my parents (using miles to upgrade to C), and the price skyrocked last week from $348 to $700+ for p.s. in Y. I had not seen it above the $500s for advance purchases since being introduced. Any insight into the jump?

(Also, all the flights I was looking at have row 9 booked solid which is a little surprising to me 5 months in advance. When I flew p.s. last Spring, I had no problem snagging two seats in row 9 both directions only 2 months in advance).