I`d keep an eye on them
Mites best way to spot them is by the chewing damage they do to fan leaves you`ll see the scars normally before you see any webbing
Just hope its a bad root pest like root mites because I hear they can be a bitch and I know thrips in the rootzone can be a cunt to get rid of, keeping the numbers down till harvest is easy but having some thing you can re-veg, nope and I have to chuck the coco away when it gets thrips, so that`s added a lot of extra work and some extra cost, I mean 10 x 70L coco blocks is around £40 to £50, ok not the end of the world
but being able to re-use my coco and perlite mix would make life a lot easier but them cunting thrips stop us doing that