The lady must've had a bad morning and looking to pick on someone to share her miseries with. Actually running out of the store to nag someone over a cig butt... LOL walking away was the best thing you could've done, bet she complained about it half the morning to the other customers.
The only thing I've heard about smoking @ gas stations is that smoking is prohibited within like 50 yards or something from the gas pump. I've never confirmed the validity of this, so I may be wrong. Don't know how much the fine, if any, would be. But then you weren't even by the pump, so that's just ridiculous.
Your post reminded me of when I got yelled at by some crazy chick when I went to Griffith Observatory last year. I know some of the local mountains suffered from widespread fires, and I just wasn't in a mindful state really enjoying the hike from where we parked towards the observatory. OMG, l never even had time to take a second hit, before another hiker completely dead stopped me in my tracks, lectured me about how I could even think of lighting a disgusting cigarette that was destroying the parks and mountains nearby, was I blind not to see the warning signs along the road that it's ILLEGAL and I'd have to pay $541 fine, blah blah blah. She was talking so loud in such a serious tone that everyone walking by us slowed down to watch/listen. Caught me completely off guard... BITCH, all she had to do was point out the sign and I would've put it out. I was so shocked holding my cig the whole time she was going off on me, I didn't know if I should just throw it on the ground and have her yell "FIRE!" or step on it or what! Took me a few seconds to snap back to what was going on... until she took a small step closer to me with her dog like she wanted to fight, eyes piercing @ the cig my fingers are holding, saying, " PUT THAT OUT NOW!"
What a SPAZ!!! I don't get it. It was a really beautiful day, nice weather, sun was warm and fuzzy, lots of park visitors walking along side of the mountain road, typical family crowd... we'd just parked, I lit a cig without even thinking looking forward to the long past-due visit to the observatory since it got its facelift. Then BAMM out of no where a cigarette nazi attacks me like she owns the park. I guess I'm still shocked thinking about it now. I can understand if I threw an attitude or ignored her... but nope, I never said a word, waited til she was done and said, uh.. is it ok to put it out on the ground with an obvious forced smile and then said chill the frak out, no need to have a heart attack as we walked away.
Anyway.. sometimes strangers can get so out of control offended, or act like as though they are intentionally targetted for whatever they're tripping on. Just say it, no need to bark it... what can you do right?