first things first, that first post was a joke....kind of like hookers and blow. now that we've got that out of the way, research has shown that addiction can occur within days, not years of nicotine use. some people are also more susceptible to nicotine addiction than others, so just because you didn't have any physical side effects doesn't mean that everyone is so lucky.
i have a good friend who is the same way. he can smoke and smoke when we're partying, and then just put them down for days on end. me, not so much.