I've always thought it good idea to tell them weather it was the law or not. It's just another reason for thme to engage in some dickery if they are not too keen on the unwashed masses having a gun. I mean, you end up in court for what ever comes out of that situation toy have the fact that you informed the officer in a respectful manner that you where armed so as not to create an overly stressful situation.
If state law allows then there is no reason to do so and I would support that. It is your right after all. I just don't handle it that way and it has always worked out for me. More often than not it will come back that you have a permit if they call your plate anyway. And if you're getting a ticket they are going to run the plate.
I have no problem with police doing their job and I understand it can be very stressful. For the most part I will do what I can to be respectful and keep everything as calm as I can. If they choose to get into a little dumbassery after that then it's on them. I do believe that they should recieve a degree of respect for the badge at least until they show they are not worthy of such.
Like I've said a lot on here. I have and still do carry open when I choose to. A lot of cops have been called on me over the years. Now a lot of these men and women know me to a degree and we usually end up talking guns after they see they got called away form dinner or something on a asshat call. That's not their fault and I am still the man reported with a gun. I've made a lot of cop friends due to those calls though. Being nice is a good thing as long as you are allowed to do so.