Also, for future reference, if you're on the UAL seniority list there are two available seats, even if there's only one in the cockpit. Because some have one and some have two there's an agreement that if two pilots need a jumpseat they'll block a passenger seat for the second pilot if the plane only has one cockpit seat. From the union,

"For 757 aircraft that do not have a second flight deck jump seat, United will ensure availability of one confirmed cabin seat for use by a Jump Seat eligible United pilot. Access to occupy this alternate seat is limited to United (s-CO & s-UA) pilots, when more than one request for Jump Seat access has been made at least 20 minutes prior to scheduled departure."