My best advice - if they do come just let them in. That way they are not tearing through your house. Invite them in and let them look around. If they do not have a search warrant then they cannot legally so they have to get your permission although probable cause would be to have seen your plants so they can get a warrant from that. This is tricky but really marijuana is not legal in this country whatsoever so even if it is medicinal they can still do whatever they want because they feel like that is part of their duty. I think growing indoors is the best security precaution in general. Really I think somebody told them you have plants. Sounds like they came and went over your house a few times to make sure they got the right one. They always say "Never tell anyone!!" Easier said than done when excitement is involved.