Oops. Double-checked everything (I thought) before submitting but missed that one. Well, that explains why I didn't see it on the https://news.ycombinator.com/ask page.

... And I don't seem to have the ability to edit the title of my own post? Huh. I would have expected to be able to edit it. HN's UI is deliberately simplistic, which is nice most of the time, but either I'm missing something obvious or there's a bit of functionality missing.

Shrug. Well, if there's no way to fix it then I'll wait a while and re-submit with a correct title.