Opinions will vary I think. When you remove him from the water bowl do you see any black dots floating in the water bowl? They will look like poppy seeds. If not I would personally wait, just my opinion. It depends on what you mean by treating it. In my opinion treating for mites is a multi-week process. When my Bluey had mites, I had to dispose of all substrate, bleach the enclosures, bleach the plastic hides, soaked and baked wood decoration, treated the enclosure with Provent A Mite, lay down paper towels, a water bowl and hide, thats it, then treat the animal itself (depending on what you are using to treat the animal, it can cause drying out as well ex:reptile relief), check for mites and repeat treating the animal weekly until there were no more signs of mites. In my opinion it is good to take preventative measures for mites such as treating your enclosure with PAM when you do deep cleans.
Poured out his bowl and there were specs but I smushed then between my fingers and it was just substrate.