Ben, you posed a good question.
Working bees at night is asking for trouble, but I can see your point.
Consider the vapors of OA are deposited on the comb, inside the hive body,,, everywhere. When a mite crawls out of a capped cell and make contact with the crystal OA the mite is doomed. The vaporous of OA with turn to a solid crystal as soon as the vapor touches a cooler object: a bee, wood, wax basically everything that is cooler. So a returning forager is going to make contact with the crystals of OA upon returning to the hive.
Now Honey is naturally acidic, there should be a bit of repulsive, acids are attracted to bases and Honey is certainly not basic. However I am sure there is some, very little acid absorbed by the honey. Consider OA is a natural component of honey, broccoli, spinach and so on.
I do not treat with OA until after I have extracted my honey. Also I do not know how long OA remains active in the hive.
I hope this answers your questions.
Blessings