It's a design change based on a submission when the Washington quarter was first being considered.
govemint.com -- "The obverse of the American Women's Quarters program will continue to feature George Washington. However, the traditional George Flannagan design will be replaced by a design of Washington that Laura Gardin Fraser created in 1932! Gardin Fraser was one of the most prolific female sculptors of her time and today is praised for both her numismatic and sculptural work."
govemint.com -- "The obverse of the American Women's Quarters program will continue to feature George Washington. However, the traditional George Flannagan design will be replaced by a design of Washington that Laura Gardin Fraser created in 1932! Gardin Fraser was one of the most prolific female sculptors of her time and today is praised for both her numismatic and sculptural work."