Dont be rude or suspicious. Act like it is the perfectly natural thing that it is and dont contribute to the stigma by acting like a junkie caught with his fix. My advice is stay calm and offer them some toke. If they decline be extra nice and ask them if the smell bothers them. If it does apologise and go outside. If you smoke in there now they prob already know about it from the sweet smell.
Most folks wouldnt pick up the phone and even if they do nothing is gonna happen to you unless youre growin in your house too. Once its burnt no cop can harrass you. Be nice to your neighbour and deny to anyone else that it was you if they freak.
Youll prob either make a new tokin pal.