IME, its a bit out of the ordinary for the operating carrier to call a customer directly on an award ticket (or any ticket) that was issued by another airline. The ticketing carrier usually handles all changes (even if it's the partner flight that changed, as in a schedule change). But this isn't a schedule change. AA's PNR may not look any different now than when you booked it, because this isn't a schedule change. You are still HK ("holding confirmed") in the AA system for all flights. I think reaching out to them is a good idea. IB may be trying to pawn you off early to help their own impending cluster-f*** tomorrow at the gate. Which isn't a bad idea per se, but you don't really know if what IB is telling you is the best solution. It might be for their gate agents, but not for you.