I haven't looked into this flight, but I can tell you quite definitely that AA does this all the time. Generally speaking on a 3-class flight, a J seat is much more likely to sell than an F seat, so AA will oversell J so long as there are sufficient F seats to roll passengers forward. It's actually quite a smart move. And while it would be better if their system could, for example, show F1 J1 when in fact there's only a single F seat available, it apparently can't, so sometimes a flight will show F0 J1 when the only available seat is an F seat. (Actually, that's not a great example because I've never seen it happen with only one seat, but I have seen examples of a flight showing something like F2 J2 when the seat map shows four unassigned seats in F and no unassigned seats in J. This is a perfect example of the seatmap showing valuable, if not definitive, information.)