So I called the cops yesterday.

Yesterday I saw someone get of a vehicle who had an open beer can next to his seat, so when he got back in to drive away, I called the cops and told them which way he was headed.

I felt like I had a moral as well as civil responsibility to do this. I can't imagine how I would feel the rest of my life is someone (much less my wife or child) got killed by that driver, and I had not reported it. What do you think? Is there a moral obligation in situations like this?