Nobody tells us anything. It wasn't quite true, but she was under strict orders not to reveal her status to anyone--and she'd already come close to blowing her cover a couple of times, between Azazel and Clyde. It was probably pretty obvious that she was involved, even if her loyalties were unclear.
"Do what? Hold it in?" She laughed. "Years of compartmentalization and stress management training to deal with bitchy passengers in confined spaces. Inside...well, some days, it's hell in here."