Well in my opinion a TN character is a bit indecisive but when he needs to decide he sides on the side which he thinks that is right.
Sure, playing indecisive is one way to treat True Neutral... but a completely different (but no less valid) way is to play extremely assured that life and the world should remained balanced between good and evil / law and chaos. And so if he sees things leaning too far in one direction, taking decisive steps to counter that is important and effective in maintaining that balance.
If talking with the old man because you thought he was the dragon was part of a plan to maintain a balanced outlook for yourself, the party, and the people as a whole... there was nothing wrong with that decision.