By this, do you mean that the blinkers won't turn off when you turn, and require you to hit the stalk to turn them off? There is a little switch in the steering console that turns off the blinkers when you turn. You may need to look at this switch to see what is wrong.
The NSX has a very unique sensor setup for this. I had this problem when I first bought my car. The issue was that the steering sheel was not straight since it needed an alignment. Before you dive in to deep, is your wheel centered properly??
Take the steering wheels off. Behind the clockspring, there are 2 small tab that need to be aligned properly with the steering wheel. That tab suppose to lock the steering wheel to the mechanism that turn the signal off. I am assuming u have a stock steering wheels. If u have aftermarket steering wheel, make sure the hub kit is specifically for NSX.