Is smoking allowed in your rental agreement? If not, it’s tacky of him to change course in the middle of the stream. Did he give you fair warning of the sign?
If the rental agreement did not state this, when you first signed it, you may fall under what is called a “grandfathers clause”. In other words, this would not apply to you, since he changed the rules after both of you signed a rental agreement.
Read carefully the wording in the agreement you signed. first.