Take a pic if you can, TBH they may be springtails which come in alot of homehardware store aspens, and coco husks, They are actually nice and some reptile breeders buy them specially for more damp substrates, they eat bacterias and molds.
I agree, I was worried my substrate had mites, but everytime I changed it more would show up, but they never attached to the snake or even cared about it. They are most likely springtails and provide a beneficial service to the ecosystem of your enclosure.