A recent CCW class I attended had a portion taught by a ME state trooper. We were told there is no obligation to inform a LEO that you are carrying.

The officer said, however, that it was prudent to do so. This is because it raises the officer's comfort level when one does so. He also said:

1. DO NOT immediately start reaching the the glove box, your purse or for your wallet. Plenty of time for that after the cop gets to the car.
2. Keep your hands in sight.
3. If at night, turn on the dome light in the car before the officer approaches, so that he/she can see what's in the car.
4. And last, "Officer I have a concealed firearm permit and have a pistol behind my right hip," or in the glove box, one's purse, etc.

The name of the game is survival, for the cop and for you.