That looks like a temp problem. Also, even though you have a temp problem, the light is way to far away and your seedlings are stretching. Best thing to do if you really don't want to lower the light, paint the inside of the cabinet white or get some mylar.
Also, try adding another fan. It's ideal for temps, humidity, co2 and general airflow that you install 1 larger fan for intake and 1 smaller fan for outtake.
Also, I hope you're not misting. Even though they're seedlings, you shouldn't mist them. The drops of water that form on the leaves will heat up and will cause spot burns or even worse.