Spontaneous Politeness

Hypothetical:
You're walking down the street.
You pass a stander. He's waiting.
He's a waiter/stander. Bus, maybe. He's waiting for a bus.
He stops you to ask for a light.
"Hey, gotta light?"
Can you see it? Picture there for you?
Now, it just so happens that on this day you do have a light.
You may not even smoke, but it just so happens.
You took a book of matches from the bordello you were in the night before.
You picked up a nice piece of tinder as you were walking a few blocks back, and you have a dry sprig of something in your pocket.
You have a light.
Alright, out of nowhere, the stander/waiter spontaneously combusts.
I suppose that it's obvious that it happens out of nowhere, if it's spontaneous.
Anyway, he spontaneously combusts.
Now, do you still offer him a light?
Cause now he obviously has one.
But, you have a light, he asked, and you have nowhere in particular to be.
What do you do?
Should you put him out first? Then offer him a light?
Stop him. Drop him. Roll him?
I think I'd just say, after he has burst into flames, "Looks like your day's turning around already, buddy," and then I'd walk away.