Seems like EF is not showing the full entry or AA amended it after you last checked. Here is what I see in Sabre:
AA0142/19SEP
JFK 0830 8 10
LHR 2025
1FX CANCEL JFK -LHR -RMKS ACCT A/C N7AT OTS *0706
7JFK/AUTO REACCOM SEE N*0142SEP19JFK *0726*CRCYMG
Translation: the aircraft N7AT is OTS (out of service), so this sounds like a mechanical. Further information regarding the protection of passengers can be found under N*0142SEP19JFK, but this entry can only be made by AA personnel, not us lowly travel agents.