"Not Concealed" has been interpreted in NC to mean "easily distinguishable as a firearm, and in plain view"
When you have a gun on your right hip in a holster (assuming you are a "righty"), and are sitting in the drivers seat of a car with your seatbelt on, and an LEO approaches you from the drivers side window, your gun is NOT visible, and has therefore been interpreted as being "concealed"...
So people who don't have a CHP will take their gun (and holster if they can) off and place it on the passenger seat where it IS easy to see by a cop approaching from the drivers side.
Now, if you have a permit (either a NC CHP, or a perit from another state that NC recognizes), you are good-to-go with wearing your firearm however you want in your car. On your hip, under a coat, in a shoulder rig, in a cross-draw, whatever.
But if you don't have a "concealed carry permit" of some sort, you HAVE to keep the gun somewhere that can bee easily seen by an LEO while you are in the car.
THAT is why people are always talking about moving their guns around in their cars in NC.
Well, that, and the fact that there are a LOT of places you can't carry in NC--permit or not. Post Offices, restaurants that serve alcohol, movie theaters, any business that is "posted", many government buildings, most shopping malls, etc, etc, etc.
Hope that helps...