Spider mites alright. I'm amazed you don't have them all over the plant but maybe they just moved in recently.
They don't feed on the roots like fungus gnats and they don't actually live in the root zone unless the adults fall down into the soil and lay their eggs there which isn't their preferred method. They lay their eggs normally on the undersides of the leaves and live their lives in the canopy. Use your scope to check carefully under the leaves especially ones that have any tiny yellow spots showing on the top side.
Eggs from mites look like large resin glands just sitting on the leaf surface with no stalk like a real resin gland. They are also much larger than most resin glands and yellowish/translucent looking.
A regular magnifying glass is good enough to see if any are there and if you think you've found some then look closer with the scope to make sure.
You don't want to be spraying stuff like neem oil on your plant at this stage or the buds will taste like crap later. Even the Safer's soap will leave a nasty taste.
Mosquito Dunks are halfway decent to get rid of them in the soil or rockwool and won't affect the buds so if they aren't on the plant I'd try that.
