exactly..which is dumb..so why get a card and be legal? so you can have these douche bags pulling random inspections?
That's why you don't tell them, but don't lie to them if inquired about it.
Word gets around, even if nobody said anything... general activities associated with growing speaks to anyone with a clue about anything. Word is one of the fastest forms of spreading information, so when one person in a small town finds out, everyone in that town, and probably 4 towns in any direction also know within a matter of days even.
It's the cops jobs to find grows, legal or not, they don't know the difference between a legal grow and an illegal grow when their flying overhead, or when they bust in your door because a neighbor smelled something funny, they only know the difference once you've provided your permit to grow. All in all, make sure you do it right and you'll never have a knock on your door. Half assed jobs deserve to be inspected... potential hazards.