General George Washington in his Favorite Red Waistcoat

In the introduction to W. M. Thackeray's The Virginians in his collected works his daughter included some of his letters and drawings concerning the research and writing of the novel. In a back and forth with Fred Cozzens and William Duer Robinson is included this sketch of George Washington in his favorite red waistcoat seemingly depicted as an upside down Five of Hearts. Very curious.