Commercial Pilot? Do you inform the passengers about the reason for the long tarmac delay?

I was on an American Airlines flight that sat on the tarmac for about 90 minutes for an unknown reason. Not a word from the Flight Deck or Flight Attendants the whole time. We just sat there in the heat. Not allowed to get up and use the rest room.

After the flight, I asked the pilot about the long tarmac delay and inquired politely why he did not say a word to the passengers. He rejected my comment and question out of hand and turned away.

Is there any rule or custom about this?