If some numbskull is smoking while gassing up a running vehicle it seems to me that the bigger numbskull is the one that stuck around when he noticed the situation.
If your "spidey sense" is tingling that's usually a good indicator to leave the area. That "spidey sense" is your survival mechanism kicking in, and to ignore it is something that you do at your own peril. Yes, there were mistakes made, but I think they were made well before you went into the store.
What you are basically doing is gambling that the fumes from the gas being pumped will not be ignited by the running vehicle, or the cigar. Good luck with that. Me, I always figure I can get gas later, as it's not something I'm willing to die for.
Granted I have pumped gas into a running vehicle, and smoked while doing so in the past. What can I say, I wasn't always as smart as I am now. :) I have however learned from other people's mistakes, and try to not repeat them. I pointed out some things to you that I hope you take into consideration.
Take care and stay safe.