I would say you did right. But again, if you were legally carrying there really isn't a need to let him know. Hell, he was carrying and didn't tell you did he?
The fact of the matter is that you may not have been legal with the pistol on the seat and not on your person. But you were polite and offered no resistance or argument and that means a lot.
A few years ago I blew by a trooper faster then I should have and when I looked at him he nodded. When I looked in my rearview he pulled out and was coming my way. I didn't even wait for his lights to come on and pulled over. He thanked me for not having to chase me as I handed him my license, reg, and proof of ins. He went to his cruiser and came back, handed me my papers and a warning and I was back on my way to a pheasant hunt.