Thanks for the link, EnhancedByCO, There were both involuntary and voluntary changes to the itineary since February.
I think a complaint to the DOT may be appropriate, It's not unreasonable to argue that the date that the air transportation was "sold" was in September, when I exchanged my valuable OnePass miles.
In spite of changes that the CO claim caused a "reissue" of the ticket, and thus the liability for the charge, it's the September transaction date that determines the ultimate validity of the ticket. (One year from the date of issue)