Are spider mite eggs in store bought soil a common problem?

I'm trying to switch my garden from hydro to soil and the 1 plant I grew recently got big and beautiful but after a defoliation I noticed a bad mite infestation. The clone was brought in from another garden and in all likelihood the clone was infected. I read on another garden website that sometimes soil contains eggs that can hatch and infest a the plant. I'm wondering how likely the soil was the culprit versus the potentially infested clone? I run a pest management routine as a preventative but I'd hate to worry about mites being brought into my garden every grow cycle running soil. The best tasting pot I've ever grown was in soil though so I'm determined to switch back. I've just gotta get some more info on dealing with pests that are common in soil.

Spider mites lay their eggs on the under side of leafs. So not really likely to be in soil unless it's reused stuff from a time you had an infestation.

Yup. Likely the clone