Call me cynical but I think she's playing both sides of this one. She was probably nodding in agreement when Chavez was speaking and then saw the millions of American eyes directed her way to see if she was going to have anything to say in response. She wisely decided to side with her President rather than a foreign dictator.
One of my coworkers made the comment while watching Chavez's speech to the UN:
"If he keeps going on like that, they're going to make him DNC chair."