Both flights had gone and both gates were free. 405 and 406.
When AA landed it was the busiest time for L/H passengers and as they missed their slot so getting a stand straight away was unlikely however the stand where it was allocated there was a hydroponic leak and an aircraft was not towed to a remote stand for a number of hours.
I only recall such a long wait once or twice and that was when a T/A flight arrives 60 minutes ahead of time before any short haul departures took place.
seems someone dropped the ball somewhere as that's an appaling customer experience at the end of an overnight long haul.
If you fly the route with AA, it won't be a shock as AA92 manages an on time performance of just 40%!