Couldn't tell you why but the past few weeks, air force one has been quite active. You can check the presidential TFR's on AOPA.ORG, they're usually on the home page(if not, look on the far right of the page, under quick links, click NOTAMS,TFR, then flight restrictions) and you do not have to be a member to view them. Maybe this way you can try and catch it again and actually know when it will be around.