It could just be because you disturbed them to do the treatment, or maybe there's a scent to them that we didn't know about that the snakes are picking up and trying to "investigate".
Is it getting near feeding time? That could also be it.
By the way, were you treating the paper towels as preventative measures for mites or because they actually had mites? If they actually had mites, then I'd guess that's just them reacting to the mites and presumable discomfort from being covered in scores of little blood-sucking bugs.