I hope you’re not serious. Do you really think it would be becoming of the Blessed Virgin Mary to smoke a cigarette?
At Medjugorje (if it is to be believed), it was the youths smoking cigarettes, not Our Lady.
It's a hard thing to imagine, but if smoking a single cigarette (as opposed to yielding to temptation to habit which could be dangerous to one's health, and often is) is no sin, then if they had existed in Palestine in the first century, then I can't exclude the possibility that she might have done it to help with digestion (and it does), similar to how one might have a cup of coffee. Tobacco is an herb of the earth that can have medicinal uses, again, digestion, calming of nerves, and so on. I am forced to eschew tobacco (at least until my Medicare kicks in three years from now) to remain in compliance with my health insurance (they impose a $200/month surcharge for smokers), but I can't condemn occasional usage of it as a sin.
When I was working, the surcharge was $50/month, which I was willing to pay, but not $200. I received my first Social Security payment last month, and even with that, my pension, and my 401(k), money is tight and I wouldn't even be able to afford the $50, let alone the $200.