You'll never know. Would be interesting to find out the flight # and see what EF shows - maintenance vs. connecting pax.

That being said, it certainly wouldn't be the first (or last) time that AA lied to passengers. I've seen it multiple times where they make crap up that just doesn't pass the BS-O-Meter. Things like UA and AA both flying OKC/ORD at the same time and one is delayed because of weather, the other isn't, etc. Airlines should absolutely be challenged and held accountable when lying to customers.