Difference In Finishes Between P And D Modern Quarters Or My Imaginaton?

Our local coin club used to give out current P and D quarters and sometimes half dollars to the members as prizes. These coins came from uncirculated rolls, not from mint sets. I always said that I could tell which one was a P and which one was a D even from the reverse due to the difference in the strike. P quarters have almost always been more satin like and D quarters are more brilliant. The same for half dollars. I also buy S quarters to put in my set individually (from dealer rolls) and the S quarters are even more brilliant than the D quarters.