This happened to me too on Aloha Airlines from HNL-SNA. I requested an aisle seat and was assigned 1C, when I got on the plane, Dr. Robert H. Schuller of the CRYSTAL CATHEDRAL was seated there. I politely told him that he was in my seat and showed him my boarding pass. The jerk didn't even look at it and told me "No, you're in 1A, I always get an aisle seat." I again attempted to show him my boarding pass with 1C printed on it and he still insisted that I was in 1A. Anyway, by this time coach class was boarding and it was a full flight, and I didn't want to obstruct boarding in the single-aisle aircraft (B737-700), so I just reluctantly relegated my self to 1A. Fortunately, no middle seat and no hygienically challenged passengers up front.