The same thing happened only once to us about 10 or 12 years ago in Ft Lauderdale and hasn't happened since. They didn't give us an explanation like they did for you but in those days not that many people were carrying their own bags with them like they do today.
Most times we've been told from the people outside the terminal (giving directions) that the bags can be checked and you don't have to take them with you but if you tell them you prefer to carry them yourself, there's no problem.