I finally got through to the call center this afternoon, another 40 or so minutes on hold. They told me because my ticket was issued before August 31, I could make changes any time. The August 31 deadline is for issues tickets, I assumed that meant reissued tickets too, but seemingly not.
Of concern is that while I was trying to change both outbound and return legs of my trip, and only the return had an involuntary change, the agent said only the return could be changed without paying fare difference. I don't think this is correct. I hope not anyway. I will try calling back, but hoping someone here can clarify?
A trick to get right through to QR reservations: Press 2 that you’re a travel agent.