Should we be surprised? From Washington Post:

The government of Iran has told the International Atomic Energy Agency that it is building a previously undisclosed uranium enrichment plant for making fuel, the nuclear watchdog agency said Friday.
President Obama will call attention to the existence of the underground facility in an early-morning statement to reporters here before the opening of the G-20 economic summit, and will say that Western intelligence agencies have been tracking the facility for years. U.S. officials said Obama decided to disclose the program’s existence after learning that Iran had become aware that it was no longer a secret.