Not so much a fire, but an explosive fireball. Probably not a huge risk, especially if you have good exhaust, but with explosive fumes, I don't think any risk is worth taking.
I know you like anecdotes, so here are a couple. Years ago I was doing finish work on some cabinets on location, which was a garage turned spray booth. I hired a guy to help me move material. We would spray a batch with Laquer and after it flashed off, open the garage door to clear the fumes. One time after spraying, I hit the garage button and as the door is rising, the dude lights a cigarette while the room is still swirling, full of fumes. I literally dove under the door, expecting to be burnt to a crisp. Nothing happened, except helper dude was sent home.
What caused my panic was knowing a guy who was in a similar situation working in a basement when a carpenter open the door while smoking and ignited the fumes. My friend Paul was badly burnt and lasted about a week before he succumbed. The carpenter survived, but was also burnt bad and horribly scarred, physically and mentally.