David, when you vapourized the colony(ies) did you have all the gaps/entrances, etc. closed right off for 10 minutes? That is crucial to success of vapourzing with O.A. If you have screened bottomboards, that must also be closed off, as air tight as you can get it. What kind of bottomboards do you use?
The fall before last when I did a consecutive number of mite counts after I vapourized the colony, (using sticky boards), I saw dead mites for about a month. At that point I gave up because I was sick of putting the sticky boards in.
When I vapourize my colonies, I do it usually the first week of November. Eeks, that is now, smiling. That way I can be pretty much assured that there is no brood present and I don't have to repeat the application until late spring. Those are my two treatment dates a year. Late fall, late spring, that is it.
In the case of an extremely heavy mite load (which I haven't had), it is imperative to do the vapourizing earlier, like when there is brood, and to a repeat again, to get what was buried within the cell, eating the larvae, ich, when the mites emerge.
It is normal to see the mites continue to drop for quite a period of time. As I said, I saw them still dropping even after one months time. If you secured up the hive well enough, that a good part of the vapours did not escape (it does not have to be 100% airtight, but the more airtight the better of course), trust that the vapourizing is working its magic. O.A. vapourizing works. As does O.A. syrup trickling. But, the trickle is only to be done once a year, whereas vapourizing can be performed at any time that one feels necessary.
I know your worrying. I am a worrier too about things. But it sounds to me like things are being done right. But, still, please answer the questions that I asked of you, it may help if I need to make further comments. Have that great, most awesome day, health. Cindi