So, if you can get a clearer photo, I think they look like symphyla, which are tiny millipedes. Hard to tell though in the photo.
I can tell you my history with potting mix. I do not buy organic anymore because it's not sterilized and I've had problems with different types of bugs. One time I even found out there was unsterilized bat guano in the soil. Sterilized, ok- unsterilized, no.
If you are worried about the plants you've already potted, here is the way to check for bugs. Take a couple of potato slices, and lay them on top of the soil- kind of push them slightly into the dirt to make contact. Leave them at least 4 hours, or overnight is even better. Then remove the slices carefully, place on a paper towel, and look with a flashlight and magnifying glass. If there's bugs, there will almost always be one on the potato. They may be tiny. I found symphyla by using the potato- apparently they like it.
But I know how you feel- frustrating when you're trying to do things right. I would at least return the potting soil that you just opened.
