Hellrazor - Yeah miracle grow aint cool. Could be your soil is just to hot for seedlings. Those plants are very young!! They dont look unhealthy to me, so honestly I wouldnt worry to much. At least wait until they get some fan leaves Humidity shouldnt be a problem, seedlings like a lil bit of humidity. Oh and dont jack threads.

Zild - Are they wilty? or just curled like Hellrazors, or just at the tip? I would def fill out the plant problems forum! You might be having the same problem as well, with organic ferts added the soil might just be to hot. Seedlings like plain old dirt, they dont need any of the fancy stuff. Especially since Mushaboom has the same problem.

I would just go get some seedling starter mix (luckily its really, really easy to find this time of year ) Good luck!