I'm not aware of any requirement to inform an LEO of having a CCW here in Pa, but I consider it appropriate to do so, at the very least, a courtesy.
Last year at this time I had just picked up two revolvers at a local gun shop and was driving home when I was pulled over by a local LEO. I was coming through an unfamiliar area of a small town and did not see the change in speed limit from 35 to 25 mph. I was really, REALLY, sweating it as I did not initially know the reason for the stop when I pulled over at the first convenient place. Also, it was the first time I had been in possession of a handgun in over 20 years! So there I am, more than a little anxious, with two handguns on the seat beside me and an LEO getting ready walk up and say howdy! Pulled my keys from the ignition and placed them on the dash, then kept both hands in full view on the steering wheel. When he came up to my window and greeted me I returned his greeting and said that he needed to know that there were two unloaded handguns on the seat beside me. He said "What was that!" and I repeated it. He leaned down and took a closer look then asked me for my drivers license.
I volunteered to show him my CCW but he declined. The rest was anti-climatic. He said that I was going a little too fast and to "next time, just watch your speed closer" and let me off with a have a nice day! If the guns had not been in view, as in the trunk, glove box or cased, I would have probably not said anything about them unless asked.
I realize that this occurrence was no big deal. It wasn't a life threatening situation and I'm sure the background check he did on my plate before approaching me showed little, but there is always the potential in any situation for overreaction. Being in a small, rural community also had a bearing. I would have kept the guns out of site if it was a large city or suburban area.
In situations like this it has always been my experience that being calm and courteous helps to ease things. I may not always agree with how any one particular LEO behaves, or anyone for that matter, but I realize that they have a hazardous profession, and have to deal with all sorts of low life and tense situations. They deserve the respect of the public they serve. Common courtesy may not seem like much but it's effects are usually positive for everyone involved.
John