Campaign appearances are usually well publicized, as are speaking engagements, if only so people know where *not* to go. This particular appearance was a limited audience -- he was signing a union-positive bill at a local union hall -- and it's entirely possible that the only people who knew he was coming were the police and people at the venue. I read the local "papers" in the morning, and there was no mention that JB was going to be in town. There was a mention of the appearance on the news that night, but by that time he was gone.

(I say "papers" because they're all on the internet now -- there's no such thing as a daily newspaper around here anymore.)