It could be any number of things. My father also goes through phases where he either gets SSSSd or "randomly" pulled out of the line for additional screening.

We think it might be because he looks so normal (60, clean cut, 6'+, caucasian, common last name). In other words, the screeners pull him over to prove that they're pulling everyone over. A similar thing might be happening to you.

On a side note, I used to work with someone who had the last name of "Jihad." He said it was tough flying pre-9/11 and - as of two years ago - hadn't even tried since.