I have a bit of an odd situation with an upcoming award reservation.

I originally booked YYZ-ORD-STL on United and STL-YYZ on AC in a roundtrip. I recently changed that to the non-stop YYZ-STL on AC on the outbound and moved the outbound a day later.

My United reservation shows the simple roundtrip on AC. When I look at AC using the United record locator it still shows an ORD-STL segment on UA on the day before my actual travel. My worry is that somehow either UA or AC will detect this as a missed segment and cancel my reservation.

I called UA and got a rather rude agent who flatly told me it was AC's problem. The AC agent was a little more friendly but told me that this is just what UA had pushed to them. Any experience with this or suggestions?