I live in Commie NY. We don't have to notify an officer if we're armed during a traffic stop. I never do, unless I'm asked to exit the vehicle. That has only happened once when I argued that my license plate lights were NOT out. (I was correct.)
Before exiting my vehicle I notified the officer, a county sheriff, that I have a legally concealed firearm and of it's location on my person. He thanked me and made sure he kept an eye on me as he tried showing me my plate lights being out. I showed him that they were in fact illuminated, and that it appeared that his bright lights made it look like they were out. He shut off his lights which proved me correct, smiled, apologized for the hassle, thanked me for informing him of my firearm and off I went.
He did not ask to see my permit, he did not ask to take the weapon (holstered at 4:00 IWB), just made sure I didn't get fidgety. I made direct eye contact when speaking with him and was not nervous. I also made sure I kept my hands VERY clear of my firearm. I really had an itch behind the holster, but that could have been very bad if I had gone to scratch it!