I hate to say it, but its pretty common with MG organic. I bought 4 small bags of MG organic because Im lazy (its for 2 mother plants) Anyway, nice cheap soil, its not bad, except for the fucking Fungus Knats. I spent $70 on Nematodes because I already had plants in the soil, but if you noticed them before using it theres a few things you can do to kill the knats and Knat larvae in the soil.
Easiest thing to do would be to pour the soil in a container outside and let it completely dry out for several days. Fungus knats and larvae need moiste soil to survice. Another option I head of recently is to Freeze the soil for at least 4 days. I will kill any bugs in the soil. You can also buy Nematodes, they are predatory bugs, you mix them with water (like sea monkeys) and they will live in the soil munching on any bugs or bug larvae. They are great for getting the larvae in the bottom 1/3 of the soil for planted plants.
Theres a few chemical products, but if you havent planted yet I would use on of the simpler methods. Dry it out good, then freeze it for a few days and you will be fine.
Its good soil...its too bad it has the knats.