We don't know the whole story, when the police interviewed the employers they may have described the employee as unstable or disgruntled which, with the internet searches, warranted a visit to the former employee. This story reminds me of a story by Adam Savage [1] where he was ordering a movie prop and received a call by the FBI and it was quickly dismissed but the agent still had to follow up the tip.

[1] http://www.youtube.com/watch?feature=player_detailpage&v=7I0...