I had this happen on a JAX-IAD flight last year, which ended up being well over two hours from the time they began boarding until the time we got off the plane at Dulles. To make matters worse, this was the first flight out in the morning, with many passengers guzzling coffee in the gate area beforehand. They claim to have made an announcement in the gate area, but I (and the others traveling with me) never heard it--if they did, it was after they began boarding seating area one. Not a pleasant flight!