Well the original poster says he had his page setup wrong and its fixed. But I know for a fact that when you start seeing clicks come in at zero value Google is watching your account. This was the behavior of an account I saw get closed. If you see something like this more than one day notify Google-worse case scenario they'll tell you to make sure you're set up right. As for the PSA thing, well very few sites have such obscure content Google can't find a match for. it happens I'm sure, especially in the early days of 2003-4 but in the last 2 years I've rarely seen a PSA on somebody's site.
he might be selected "Only allow certain sites to show ads for my account" and then bypassed from including bypass4free site in that allowed list.
Well, looking at the highlights your site seems to be very broad in targeting. I would say that causes public service ads to appear every now and then.