This kind of thing is pretty common these days. Gung ho, law unto themselves police harassing and/or arresting photographers on trumped up non-existent laws (you have to love a police department that doesn't actually have a supervisor on duty).

What with this and police chiefs found guilty of torturing suspects, the Chicago Police found to have systematically tortured black suspects over a number of years and so on, it is no surprise that this other stuff happens.

See http://www.photopermit.org

http://www.photopermit.org/forum/

(run by an apuger I believe) for endless examples

Unfortunately, in the last few years studies shown that training and professional standards across numerous police departments in the US, especially (though not only) the smaller departments, have declined. I say unfortunately, because this is my particular area of expertise having been involved in this since 1977.