The Transportation Security Administration introduced "Gateside by TSA PreCheck" in September at 13 airports, letting PreCheck members apply one to three days in advance for a pass to go through security when they were not flying.

According to CNN, the program expanded this month to hundreds more airports, including Denver International, where a CNN affiliate was able to use the benefit last week.

That expansion was then quietly reversed within days, and the Denver airport said operations had returned to the original 13 participants, at least for the time being.

Only the original airports remain bookable, per the CNN report: Mesa Gateway in Arizona, John Glenn Columbus International, Dallas Fort Worth, Detroit Metropolitan Wayne County, Wichita Dwight D. Eisenhower National, Indianapolis, Harry Reid in Las Vegas, Los Angeles International, Bill and Hillary Clinton National in Little Rock, Will Rogers International in Oklahoma City, Eppley Airfield in Omaha, San Diego International, and Salt Lake City International.

When an airport is absent from the Gateside website, there is no way for a would-be user to apply for a pass at all.

The rollback caught even participating airports off guard. CNN reports that Norfolk International Airport in Virginia only learned the program had stopped being offered there when travelers complained that they could not apply through the TSA's online portal.

The airport's chief marketing and communications officer, Chris Jones, told CNN he logged in to verify the claims and likewise did not see Norfolk in the pulldown menu. The TSA has not responded to CNN's request for more information about why access was reduced.

The stakes are practical for anyone who liked the program's promise of returning to the gate for welcomes and send-offs, meeting friends during a layover, or enjoying dining and shopping without a ticket — moments the TSA said would once again define air travel.

Travelers outside the 13 listed airports should check the Gateside portal before counting on a pass.