An armed stickup artist managed to slip away after robbing an off-duty U.S. Secret Service agent over the weekend. The perpetrator snatched a bag from the unidentified agent around 9:30 p.m. Saturday, the Tustin Police Department said. The agent reportedly drew his personal weapon and fired it, but the suspect was not located. It wasn’t immediately clear if the shooting caused injury. Want more breaking political news? Click for the latest headlines at Raw Story. The suspect fled in a 2004-2006 silver Infiniti FX35 or similar car, police said. The robbery happened days after President Joe Bide…