SNS recommends to always spray their product with lights off. It's Rosemary oil mostly, so it's not like it dries like water, it sticks to the plants and when you apply light and heat, it can certainly cause them to dry out and burn.
This is taken directly from SNS
"When applying the product take caution not to spray any buds on the plant, in doing so this could result in burning the buds sprayed."
"To reduce the chance of burning do not use under direct sunlight or grow lamps."
It also say to make sure you use Chlorine free water, so no tap unless you set it out.
Also, you don't want them to "dry out" so fast. If leave the fans off and spray them during dark cycle. The oils break down the cell walls of the mites causing them to basically melt. If you dry the oils before they've had the chance to saturate all mites and eggs, then your problem persists.