That'd be insanely surprising. First of all, if they do monitor sites whatsoever, they'd be going out of their way just to go after stoners. I mean, sure, most of us do grow and probably consume, but I'm guessing your police have better things to do than to go on the internet and check around for people growing a few plants.
Heck, they'd have to breach many INTERNATIONAL agreements to go after some people who post here, such as me, since I don't live in the States.
To sum it up:
1- Unconstitutional
2- Waste of their time for this pointless war on drugs
3- Waste of ressources
4- They can't differentiate people who just pose as growers and those who really are.
5- They can't go after people just because of posts on a site. If they did, and showed up at your door, you have the RIGHT to refuse being searched on such flawsy evidence, without a warrant. And any kind of incarceration would be just so... US-style. Like, having, to a certain point, a fixed trial and and a heavy sentence for such a light crime.