I saw that as well, but I see no official reference to a MCT at DFW on aa.com anywhere. I just pinged the twitter DM folks and they said that 40 minutes is "sufficient" and would have to charge me a fare difference if we wish to change to the later connecting flight in advance. So, we'll roll with it I guess. As long as we get out of HNL on time, it's likely we'll be at the gate in DFW early.
Was this due to a schedule change? If so, call AA. They're usually accommodating when a schedule change results in a tight connection. At least IME.