I imagine he was noticed and, being the Mayor, recognized (or identified himself in some way to someone to whom he talked). I think the school system needs to hire a security expert and he needs to draw up guildlines as to what adults should be looking for. A well-dressed man in a suit, talking, where the people to whom he's talking to don't react in a negative way or "report" him to a teacher or administrator, obviously isn't a threat! At the least, some teachers should be buttonholed and told it's their additional job to pay attention to what's going on in the halls, assemblies, etc. during breaks in the schedule. Even my county has "ads" telling citizens what should be looked for (in relation to terrorists/home security, 9-11) and having a "pop-quiz" when no instructions have been issued that you are supposed to watch for people you don't know and confront/tell someone/etc. would make me angry.