According to http://handgunlaw.us/states/pennsylvania.pdf you do not have a duty to notify when stopped, but looks like you have to produce your license if asked:
Title 18 Part I. Article G. Chapter 61. Subchapter A. § 6122. Proof of License and Exception.
(a) General Rule.
When carrying a firearm concealed on or about one's person or in a vehicle, an individual licensed to carry a firearm shall, upon lawful demand of a law enforcement officer, produce the license for inspection. Failure to produce such license either at the time of arrest or at the preliminary hearing shall create a rebuttable presumption of nonlicensure.