I had this issue with my auto wipers back this summer. Dealer had to replace the interior rain sensing module mounted on the inside of the windshield. The problem was first, intermittent and then as time passed it became a dry swipe each time the engine was started. Since the replacement of the rain sensing module, I had no other occurence of this ''dry swipe'' thing. It looked pretty silly when I started the car on a bright and sunny afternoon with not a cloud in view.
2012 Oxford White SEL Sedan
303A + winter package + Moonroof + 16'' OEM