The following is just "brainstorming" I haven't had this problem or tried any of these solutions, but they seem reasonable to me, so I figured I'd share.
1. Leave it open and let it air out (like Dixie said).
2. Put in a small container (like mabe an open film containor, or a shot glass) full of baking soda, that allways seems to work in the fridge.
3. Fill the humi with dog rockets, let them soak up the smell while trading back some tabbaco aroma.
Lastly, and personally I don't know if I would try this one, I read somewhere a suggestion about wipeing down the inside of a humi with vodka (or other nuetral spirit) to kill odors and mold spores. Again, I don't know if I'd try it.
Oh well, there's my suggestions (for what they're worth ??? ) I think after any of them (except #3) you will have to re season it) Good Luck