I Saw Something Odd

There were lines in my lighters fire, like a grid. But they disappeared when I looked directly at them. After letting the flame go out and lighting it up again, I couldn't see them at all anymore, indirectly looking or not.
Before I let it go out the first time, I moved my hand into a different position, rolled my head around, blinked a few times and then looked again (not directly) and I could still see the grid.