get my license and registration ready.
You really shouldn't do this until told to do so.
A guy at my department pulled a car over a couple years ago for speeding on a rural road. The guy reached in the glove compartment to get (what the officer assumed was) his registration. When the officer was even with the rear door, the driver turned, stuck a gun out of the window, and shot the officer 5 times. The first bullet went through his forehead.
Driver is now on death row.
Long story short, when you reach for anything, cops get nervous.
Saying the officer asked you to approach him reminded me of this video. It's graphic... you've been warned. LINK