Michelle is flaunting her arms on purpose. A publicist for the campaign commented a long time ago on her arms, in order to give the press something complimentary to focus on. They are playing 3 card monte with the Oprah crowd. (Credit to the freeper who called it that already today.)
Enough already with the arm exposure, save it for formal events and warm weather. Is she going to start wearing sleeveless winter coats?
She is showing her arms to take the focus of her bowed legs