Ok, some D gate history.

The D gates were originally D1-D5. 1991-1992, the Port spent $80 million (paid through landing fees) and added gates D6-D11, giving Alaska more space for expansion, and remodeled the entire B/C/D concourses to give a brighter, more airy feel. Around 2001 AS added a 12th gate to the D concourse, which was sandwiched in between the present gates D8 and D9, so there were three gates on that corner there facing the N Satelite. Needless to say, the boarding area could get pretty crowded at times. Apparently they could not get any 739s or winglet-equipped 737NGs into this new gate, so sometime around 2005 or 2006 they removed the extra jetbridge and went back to the 11 gate arrangement. So the current gate D11 was briefly gate D12, and D10 was D11.