Yep. I may have remembered it because it struck me as a particularly useless kink to invent, mind you. Still, it led to that wonderful preface, and a most enjoyable example of comic melodramatic smut (a rare genre indeed).
I decided part-way through that you'd probably written this (on the basis of your use of "non-chalantly"), but because the story had clearly been grammar- and spelling-picked (which you're normally averse to) I wasn't brave enough to publish my conviction. I also thought that, if it was by you (and the first non-Snape fic of yours I can recall), you were an even more flexible writer than I'd believed.