I've only run into two of those "random" traffic roadblock things in the past few years and both times I had my license ready when I got to the officer at the stop. As traffic was backed up a few cars on this dark two lane road, I had time to get the license out.
When I pulled up, I handed him the license, he looked in the Jeep, handed me back the license and we moved on.
I'm thinking both times it was more of a drunk driving check point than anything else.
I made no mention of the gun on my belt, the gun in the glovebox or the one under the rear carpet well.
Driver's license only at this type of stop unless we would be asked to exit the vehicle.