AA.com Seating Assignment Problem?

I have had my confirmed seats for my flight around two months now, but ever since our flight was booked out it has said " We apologize we are unable to pre-assign seats for your reservation. Please check back on AA.com or obtain your seat assignment(s) at the airport on day of departure." On the flight map it shows only one available seat on our flight. Our itinerary still shows that we have our confirmed seats still though. Does this just mean that we are unable to change seats? Or is there a problem with my seating assignment?