Colorado law is you can have a gun in your vehicle at anytime loaded with one in the chamber! By law you don't have to tell a police officer you have a gun if pulled over, yes if asked! I would never leave it in the vehicle and I go Friday for my concealed handgun permit! There are so many car jacking anymore I'm letting them know ahead of time it's only going to take one round to stop the threat!
The LEO who pulls you over has every intention of going home to his family after meeting you, and that resolve is central to his serivce. The last thing you want to do is give him a good reason to wonder if you represent a threat to him seeing his family again. That's before he asks you anything, before he walks up to your door, before he gets out of his cruiser. For his sake and certainly for your own, it is very unadvisable to have a window sticker or bumper sticker that puts him on edge. That ought to be obvious.
What may not be obvious is that a car with stickers on it, even just a few, puts LEOs on edge. It tells them that the driver may have an axe to grind, an attitude that they may need to be concerned about, etc. It doesn't matter what the stickers are. You could be extoling the virtues of Mozart, meditation, and organic gardening, but if you have several stickers on your vehicle it puts an LEO on edge. That's just the way it is.
When he gets to your door and asks for your driver's license, give him your concealed carry permit at the same time if you are armed or if you have a firearm in the car. It's simply polite and respectful to the officer, and it's a technical foul if you don't. Doesn't matter if he asks. Tell him first and assure him that you are legal by giving him your permit to examine. You do not want him to find out later if a pat-down becomes necessary.
Play fair with an LEO and you will receive polite, professional, gentle treatment 99 times out of 100. Give him cause to question your character or intentions, and you could ruin your own day in several ways that you will greatly regret.