Young Smokers?

I've been smooking since I was 15 years old, and always kind of thought "Man, I sure was young when I started smoking" and always thought of it as something kind of rebellious. But, yesterday, as I was walking through town minding my own business, I suddenly saw myself being approached by two little boys, about 12 years old. Although they were dressed kinda punky, you could see that they would have even made Justin Bieber look like an old man.
Anyways, they obviously saw me smoking and straight away asked me for a fire, and me, being the naive bastard I am, instantly thought "why would those little wannabe punks want a fire?"
After being caught totally off-guard when they pulled out a pack of Marlboro Menthols (baah), I asked them if they weren't too young to be smoking.
They just looked at me like sheep and like they never heard of smoking being illegal until you're 18, and I asked them politely to hand me their fags and fuck off.
Well, they did so, and I got rid of those nasty menthols.

So, was my reaction correct? Is it okay to stop those kids from smoking, although they will surely have bought another pack by now?
Or should I just accept that kids will always start smoking at younger and younger ages?