I booked a trip using miles LAX-SFO-LHR-PRG. I booked through AA but the flights are booked on BA. The first leg, LAX to SFO is the leg that has me slightly confused. ON AA it says "You are traveling on a carrier other than American Airlines or American Eagle; please call BRITISH AIRWAYS for your seat assignment." But on BA it says that I can't choose seats on BA's site I have to do it through AA. The flight is AA 6047 operated by Compass Airlines. I was able to choose seats and they show on AA but not on BA.

Should I be worried?