Why would having guns in the car lead him to assume that you are criminals, especially when your friend let him know ahead of time?

I was taught to give an officer my carry license along with my driver's license when pulled over for a traffic citation. I've only been pulled over once while carrying, and the officer thanked me for the head's up and did not ask to see the weapon or for me to get out of the car. (I also just got a warning )

We're not living in a police state (yet). Exercising a basic constitutional right should not require you to go through extra hassle from the police during a minor traffic stop.