AA has a habit of changing flights without notifying you.

I do not know about the additional stop, but I do know that on several occasions, when tourism was at full capacity, we would find out that our flight into San Juan was arriving after our connection to Beef Island had departed.

Check your reservations early and often. There was never any problem getting flights changed, but I shudder to think what would have happened if we had not checked months/weeks/days ahead of actual flights.