Sounds to me like your DS has at least a little bit of pyro-fascination in him, which is also found in some on these boards and many males of the human species.

Sounds like the next time he does it without supervision and gets caught it might be time for some discipline, if not already. What and when is of course your call as a parent. Otherwise, they seem to learn fast and did a commendable job.

The key to playing with fire is to not get so out of control so as to create damage to persons or property of value. The key is to not fear it too much, and to give it a healthy respect. A fine balance.

A level of comfort around fire helped me tonight, because of a few flames which I quickly and easily extinguished. But, I've also got some pyro-fascination.