Not sure how many people use the mobile boarding option (I usually do not) but yesterday's security line at DIA was an eye opener. All mobile boarding pass scanners were down. TSA was telling any mobile pass holders they need to go to their respective airline counter and get a paper ticket. You can only imagine the amount of arguing and frustration that ensued. I am sure many people missed their flights yesterday because of this. Standard TSA line was "we recommend that whenever you travel with a mobile boarding pass to also have a paper copy as back-up."