Mites

I would say spider mites aren't that bad during mid-late flowering, as the risk of having bud-rot after spraying buds, take a lot of care to do it on a hot, dry, sunny and windy day if possible.

Little dawn soap mixed with water will kill living mites. Dont mix to much if your spraying buds. Wont hurt but you dont want soapy tasting smoke, can also wash buds when finished growing. All depends how you want to go at it. Your spotsmdont look like mites, mites suck the underneath of leaves and leave tiny white spots, sometimes hard to see. If you have a magnifying glass check the undersides of the leaves. Their tiny little guys. Cheers