Im going out on a limb and thinking it has alot to do with watering and your soil. For starters i would personally use a seedstarter medium in a small container (alot of people use solo cups) while its in the seedling stage. MG tends to run too hot for most seedlings. Your seedlings look to be in a pretty big pot right now. This can cause you alot of problems when it comes to watering. Over watering especially. Your lights are sufficient for the little ones but once they get bigger you will need more light. More light=more heat. You will definitely need some kind of ventilation.
Check out alot of the grow logs on here and you will find alot of info. Especially check out some of the First grow logs. Alot of people have added alot of great info to them that will help you figure things out. Good Luck!