I've never heard of seeds carrying any kind of pest within it's genetics or coating....are you starting them in a soil-mix or peat-pellet? Most likely you have some bad soil or something you mixed in your soil-mix had the eggs in it. Since the root is where the moisture would be most prevalent, the eggs would hatch there first.... best bet - dump the whole thing and get rid of your soil-mix. It'll save you tons of headache in the long run. You may even want to try 'baking' the soil you use next, to make sure you don't get more of the mites.
This is simply one of the biggest reasons some peeps will ONLY grow from seed - it's one of the major risks of growing from clones. (not that it applies to you in this case.. )
I just bought some neemazal t/s but all the info is in german
the seeds are just in toilet paper but mites was only in between them in my dark room, i think i just spotted them early, i have just noticed a 1 more on a leaf on another plant, so when i get up in 8 hrs i am going to kill all.
if anyone know the best way to use neemazal that would be a great help