If you approached in a non-threatening way and the driver assumed a fighting stance, you may have feared for your safety (considering the previous action) and been well within your right to defend yourself with a pre-emptive blow. I applaud you. They will think long and hard before trying that again.
I had an incident with a young lad at a shopping center entrance. I was on the road approaching the entrance, the young man saw me, waited until I was almost to his car, then he gunned it like he was going to pull out right in front of me, causing me to brake hard. He hit the brakes and laughed. I stopped, got off my bike, walked up to his window, asked him if he would find a knuckle sandwich funny, he started stammering, at which point I emptied my bottle of Gatoraid on his dad's front leather seat, and rode off.