Appears this marriage was the second for Mary:
Marriages--Virginia to 1800: at Ancestry.com
Virginia, Greensville County
Ellis, Ira married Mason, Mrs Mary on 03 Nov 1795 in Greensville County, Virginia

In the Virginia marraige records book, there is no widow indication for Mary Mason.48

The history of "The Outlaws of Cave-in-Rock" is one of those extraordinary records of early criminal tragedies in state history which have always challenged human interest and will do so to the end of time. Beginning with the mystery that enveloped that famous "Cave in the Rock" almost opposite the sinister Ford's Ferry Crossing in Crittenden county, the author has collected all the stories that gave its very name a terrible import. He has pursued through scattered court records from Kentucky down along the old Natchez Trace the dreadful story of the Harpes. In the course of it he solved the long closed mystery of Samuel Mason, brave soldier of the Revolution, who fell on evil days, became a notorious river pirate and highwayman and perished miserably.