Yeah, BitD uses them in a different way, as I understand it. DMG2 for 4e does talk about vignettes, though I don't recall that it quite describes using one in precisely the way you've done here. Certainly it is consonant with various literary strategies of organizing stories 'in media res' which you see pretty frequently in movies/TV. The main characters are first seen speeding to the climactic confrontation in their air raft, and then we start to learn how they got there... Much of the action is flashbacks with the final outcome resolved at the end. The Usual Suspects is an obvious example which kind of layers the whole thing because the interrogator keeps digging back further and further.It's kind of you to say so!
I'm sure it's not a technique that's original to me or this scenario. But from my point of view, I invented it for this scenario to solve a particular structural problem: how do I ensure there's a conflict that points strongly towards a morale check (one of the ingredients) while avoiding a railroad?
EDIT: I'm familiar with BitD in general terms, but I think my flashbacks work differently. Also the old 3E/d20 module Three Days to Kill doesn't use flashbacks but does have a tight structure with an ultimate scene - I've never played it but have read it and thought about running it, and it influenced me a bit too I think.
As you say, some RPG scenario must have used it before. I am not able to recall such though. It would be a nice ploy to use in Paranoia! hehe.