WASHINGTON, - U.S. President Barack Obama set off metal detectors Friday as he inspected a gatehouse on his way back to the White House from a party at Blair House. "I just wanted to see what it was like getting in here," Obama said. "I think I beeped a couple of times." Obama shook hands with gatehouse guards at the Northwest Gate and talked football as he returned to the White House from a holiday party with National Security Council staff across Pennsylvania Avenue at Blair House. As Obama walked through the metal detector, it went off. A guard told...