Are you really changing the ticket if you don't re-ticket? Or is it better characterized as if you ticket an xONEx with a stopover you can actually have a sub-24 hour "stopover" by which I mean the ticket and taxes and fuel surcharges are all indistinguishable from that of a longer stopover: no refunds for taxes and fuel surcharges.

Another oddity is possibly wanting to re-ticket with zero changes in order to have fuel surcharges repriced at current reduced rates that can save more than the $125 ticketing fee I assume would be charged. I'm going to be asking AA about this soon, though I may wind up changing the route anyhow.

I spent a chunk of time over XMAS researching fuel charges for xONEx tickets with a view to a post in a bit (*). An example of one curious type of situation was DFW-SIN. Flying DFW-xHKG-SIN has the same fuel charges as DFW-xNRT-SIN but DFW-HKG-SIN is cheaper by more than $125.

(*: work distracted in Jan, but coming soon now: a bunch of changes to update in my draft)