Depends upon the state you are in. In Nebraska, you are required to inform. In Colorado, you are not. These states have reciprocity (Permits from both states are honored by both states), but the rules are different. Know the rules.
I have informed the officer all 3 times I have been pulled over (voltage issue burns out tail lights/turn signals at irregular intervals-flood damage sucks) and all 3 times they pretty much asked where it was and said leave it there ...... one (local county deputy) of them asked what I was Carrying, and we got to talking guns......
TheGolden Rule of Tool Use: "If you don't know what you are doing, DON'T."