Well, I got the bike back on Saturday, but I don't have a final conclusion to the story.
What I failed to mention in earlier posts, is that the bike was well-overdue for minor service, and that I had planned to take it in to have that done before winter really sets in (I ride year-round). Otherwise, I would have toughed the problem out for a bit, since, although it was balking a bit under load, it was still quite drivable.
When the dealership got around to driving the bike, they also noticed the balking, but thought it was mild enough to easily be a bad gas situation. So, rather than burning up a few hours (and my money) diagnosing a potential technical problem, they suggested that I just live with the balking until it needed another fill-up, and then see how it behaved. They were reasonably certain that, if an electrical problem (e.g. coil failure) was developing, it would get progressively worse, eventually becoming a more obvious fault (e.g. check engine light).
So, I've gotten my minor service and the bike is still behaving the same. Stay tuned for further developments.