Slow Down!! *bling-bling*

So yesterday I am driving home from work; one of the streets I often take one the way home goes between the Community Centre and the Casino. The speed limit on the street is 50km which is generally what I go at as there are usually a lot of people around. This is what I as doing as I was going past the casino and up ahead I see an old man (75ish maybe) screaming (spittle and everything), "SLOW DOWN SLOW DOWN" and waving his arms up an down at me. Because I was doing nothing wrong and was kind of amused I stopped sudden in front up him and rolled down the passenger window to talk to him. I think this really surprised him.
Before I can even get a word out he's saying "you are going WAY to fast, this is a casino, blah blah blah." I said calmly with a smirk, "Sir, the posting speed limit on this street is 50km/h which is how fast I was going". While we are talking there cars going around me that are clearly going fast than I was and I can see the old man irritably watching them.
Basically he thought I should be going 5-10km/h and I was rude. I told him perhaps he was overreacting and maybe should concentrate his efforts in getting a crosswalk put in if he was that concerned. He didn't really listen though and lost his patience with me and walked away.
I felt bad for feeling so amused by the situation but I clearly didn't do anything wrong and other casino goers walking by were clearly amused by the goings on as well.