Young guys, on average, have a reputation for poorer judgement and more impulsive, risky behavior, than, say, 50 year old dudes (if nothing else, I have managed to get to 50 without killing myself or geting incarcerated!). Have you checked what will happen to your car insurance when you hit 25 (the last "good" birthday!) When I was a brand new USAF officer at 22, I waited to buy a Pontiac Firebird until I was 25 because the insurance was going to eat me alive before then. There is a reason for that. Granted "average" does not describe any one individual of the population, but when the officer is walking up to your car, he doesn't know where you are on that spectrum, so he has to go by what he sees.
Also, a large proportion of the criminal population is made up of young males, so your appearance is probably going to raise the officer's alertness a tad.
Is it fair? eh. maybe not, but there it is.
Now, when you politely hand over your DL and CHL, and DON'T do any weird things to otherwise alarm him (like get out of the car, lip off, hide your hands, etc), then he more likely to ratchet down a bit, or at least not drag you out of the car and prone you out.
Or disarm you. btw, I DO NOT volunteer that I am armed and do NOT recommend it. As a practice I do not volunteer anything, and particularly with guns, I don't want to inadvertently spook the guy (or gal), especially if he is young -- same rep applies to young cops. (They make ME nervous.) I (and you) especially don't want to say, "I have a gun." The cop may not hear the part about the CHL, but he for sure will hear "gun" and you could very well end up looking at his from the wrong end. I go with handing over the CHL, let HIM ask if I am armed, and then he is expecting to hear something about a gun.