stress, peer pressure, being in an enviroment where family member smoke.
could be all reasons for it. what ever you do fight that urge and it should go away you don't want to start that nasty habit trust me i personally know how addicting it is.
i have that same problem, like ill be sitting there and ill notice that im holding my pen like a cigarette not knowing that im mimicking a smoker. my mom and my dad used to smoke but i think its nasty too. its weird
Whatever the causes are, I would suggest do not try to smoke. Smoking gives bad taste in kissing LOL
Maybe your friends are doing it and you want to as well? You might just need a hobbie :P
and a bumpy tongue lol