At least, I assume that's what's going on here.
I wasn't particularly concerned with whether this plant would bloom: I knew it was a Hoya, and therefore it had the potential to do so, but I'd been pretty happy with it as a foliage plant, so I didn't really care whether it gave me flowers or not. So this is a pleasant surprise.
The plant's been hanging about a foot below a fluorescent light (you know the big light boxes doctors use for looking at x-rays? It's one of those, via the University of Iowa Surplus store.), in my office, near enough to a window that it might be getting a little natural light too, when we have some. Compared to the rest of the house, my office tends to be warmer and drier, especially since it got cold enough out that the heat is running pretty consistently. Having the heat on is the only thing I can think of that would have changed for the plant. (Weirdly, one site says that they need cool night temperatures to set buds: possibly this might have happened during the transition from summer to winter, when we stopped running the air conditioning or heat at night, but that would have been quite a while before I saw any buds.)
And now, suddenly, there are flower buds. I counted four. A few of the other stems have what look like leaf buds in the same spot: I'm not sure I grok the growth habit here.
In any case, it will be interesting to see how this develops, or whether it develops. So far, in the two or three weeks since I first noticed this, nothing visible has changed, though that doesn't mean nothing's happening. Google image search tells me that the flowers are fairly standard-looking Hoya flowers, white or pink with a pink, red, or brownish . . . is "corolla" the term? Smell is reputed to be weak but pleasant; that's as far as the descriptions I've seen go. I will, of course, follow up if/when anything interesting happens.