Possible meanings of the "riddle" in Tom McGuane's story

Another fine Tom McGuane story, Riddle, in the current New Yorker; McGuane has established himself as the great chronicler of the changing times in the Northwest, Montana in particular (his friends Tobias Wolff and Richard Ford have also written well about this region and there are many similarities particularly between McGuane and Ford). This piece, in which a contemporary man looks back on an unusual, perhaps pivotal, day in his life about maybe 20 years back, and he himself, as narrator, says he cannot quite make sense of the events or even be sure which if any may be imagined rather than recollected. McGuane focuses many of his stories on the migration or invasion if you will of West Coast $ into rural Montana, whether from those fleeing the pressures of life in the tech or entertainment industries or more often from the uber-wealthy building vacation ranches and estates. His (male) protagonists play a facilitating role in this invasion, which is changing the world they grew up in or at least settled into, in their modest ways. The narrator (often a realtor, a la Richard Ford's major protagonist, interestingly) in this case is an architect, whose specialty is building models for presentation and use by other architects; he notes that "in those days" he rented a small office in town (presumably, no need for him to have an office at present - for reasons left open - too successful? only builds models no need to meet w/ clients? to un-successful? change of career?) and notes that he had a model of FallingWater on display and that his clients usually thought it was a house he'd designed. Ha! On this night, after heavy drinking to closing hour, he sees an old ranchhand on the near-deserted Main Street greeted warmly by a young many or boy, and narrator is profoundly moved by watching this encounter - he's not even sure why, but we can sense that it's out of his own sense of loneliness. On his ride home to his house out in the country (at least 10 miles) he comes across an "accident" scene, which proves to be a scam as the purported victims steal his car and take off. He gets a ride home from a woman - an ER doc - and at his home they have sex; presumably, he never sees her again. The next morning the Sheriff arrives and tells him his car was involved in a bank robbery and the driver and passenger were hit in a fusillade of bullets when they were arrested. He asks why the narrator never reported the theft of his car; narrator cannot answer this - which seems to be the eponymous  "riddle." Was it because he was not sure of his facts? Did that have something to do w/ the ER doc? So odd that an ER doc would pick him up on the highway; could he have gone to the ER and his memory blanked? Did he in some odd way ID w. the bank robber Bonnie & Clyde-like couple, see them as an emblem of what his life could - or should - be: on the run, escaping from norms and expectations, or at least w/ someone instead of out in the country 10 miles from a small city, nobody else in his life?

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