According to the "Genealogical History" of the Boone family by Hazel Atterbury Spraker (published 1922), John Webb, the husband of Mary Boone (daughter of immigrants George Boone and Mary Milton Maugridge), "d. 18 Oct., 1774, in 80th year" (Spraker, page 39, as her work appears at genealogy.com).Therefore, he could not have been an aide to George Washington during the Revolutionary War.At the next page, Spraker cites Exeter records for the birth date of John Webb, son of John and Mary (Boone) Webb, as "b. 14 Mar., 1720. (O. S.)."Spraker does not mention a death date or any military service for this Jobn Webb - or if she does, I'm not finding it.
According to a 1936 work on Revolutionary War records of Virginia by Gaius Marcus Brumbaugh, there was a John Webb who was a "Lieut. Col." during the war, but this would not indicate it was the same John Webb.I'll let you know if I find anything else relevant.