In questionable situations, I tend to ask, “what’s the downside?”. In this case, using a resource (police–although I doubt they’re going to wait on a 911 type call and respond to this first) and potentially offending the man (assuming the police find him and question him). Those are very minor and that’s what the non-emergency line for the police is for. In our community, the police messaging is “See something, say something” and, in this case, that’s what you did…as would I.