I'm getting that slightly nervous pit in my gut that tomorrow's travel is not going to go smoothly... Anyone else encoutered this?

Flew BA: LHR-DFW then AA: DFW-YVR, last month, no problems. Try to check in today for the return, and now AA can no longer find my reservation. "Unable to find your trip. Please check your information and try again." I've tried the PNR Locator (AA's not BA's) and Ticket number for the retrieval, but same result... BA says there is no problem on their side, and everything looks good. Their solution is to check in at the airport tomorrow morning.

Has an AA segment / PNR for a BA booking dissappeared for anyone else? Any ideas on solutions?