Is The "McRib" Really Made From Gym Mats?

Is McDonald's McRib sandwich really made from gym mats?

According to THIS story in Time magazine, there is a disturbing grain of truth to this slanderous rumor.  "But it's still a little disconcerting to know that, for example, azodicarbonamide, a flour-bleaching agent that is most commonly used in the manufacture of foamed plastics like in gym mats and the soles of shoes, is found in the McRib bun. The compound is banned in Europe and Australia as a food additive."