I have actually been wondering the same thing lately. I think that I saw every episode of season 35, and she made two appearences. The first was on the special, the "Street We Live on", and the second one was a very brief appearence when Gordon, Miles, Elmo, and Miles' grandfather made a band. She also appeared on the "What's the Name of that song?" DVD. However, other than that, Susan has not been on the show this season (that I know of). I dont know why, but I hope that in the next season she has a much more prominant role.