Take a look at the average age of...
Republican congressmen in 1949: 54.9
Republican congressmen in 2011: 54.9
Democratic congressmen in 1949: 50.4
Democratic congressmen in 2011: 60.2
The democrats have gotten older, but not by much more than the general population. The senate has gotten older, but not dramatically so.
http://online.wsj.com/public/resources/documents/info-CONGRE...