Okay, so a Canadian reader tipped off Gregg Easterbrook, but still, he just easily could have not mentioned it while discussing coaches who have gone for it fourth down and gone on to glory (maybe not that day, but eventually).
"Note 3: Reader Shawn Dolan of Ottawa, Ontario, reports (and bear in mind that under Canadian rules, third down is fourth down): 'In Saturday's Mitchell Bowl, the Canadian college football semifinal, the Queen's Golden Gaels faced third-and-2 early in the fourth quarter and went for it, getting the first down. Later, facing another third-and-2 near midfield and clinging to a three-point lead with three minutes to go, (they) went for it and converted. Queen's University held on to upset heavily favored Laval and secure a berth in the Vanier Cup, the championship game of Canadian college football.' "As noted, it was officially third-and-1 (more like 1½) from the Queen's 30-yard line the first time. The second was on third-and-2 at the Gaels 47. Vince De Civita and Matt O'Donnell cleared the way for Marty Gordon each time.
Again, more rigorous study is needed, but you are seeing coaches who realize an all-or-nothing third-down call is statistically correct. Sheahan, though, did it in late November rather than September.