"American Airlines got rid of its 24-hour hold feature for some customers as part of a two-week test, a spokesperson for the company told the Charlotte Observer.

The test will evaluate how customers use the 24-hour hold feature, but the company declined to comment on why the evaluation is taking place.

As stated on the American Airlines website, the feature grants potential customers the capability to hold seats on a flight for a period of 24 hours which allows them to decide if they actually want to book the ticket."

Perhaps the above offers some explanation.