I have exactly the same problem but have always put it down to claustrophobia (I have no idea whether I'm correct or not). I have shortness of breath when I'm on the ground and can't get the air nozzles to give me any reasonable output (when we taxi seems especailly bad) ... once we're in the air and everything is flowing then I'm fine. I get a similar feeling on the subway ... if I can't feel air rushing over me then I feel slightly tense. I love flying and it really doesn't bother me ... I just accept that somewhere in the back of my mind there's a part which is not comfortable.