My #1 guess would be he has a short. running .4 coils, he's probably using fairly thick wire. perhaps part of his coil is touching the deck causing a short. Also, ejuice CAN ignite if it gets hot enough. I actually ignite it when I am oxidizing mesh...it seems to burn fairly clean with no visible smoke/vapor, and will sustain a fire. If he happens to get his coils hot enough and have a big enough airflow hole, I would imagine it's quite possible.