Brakes - rough release

[Fcreigh]

I have a '98, 24 valve, 2500, 4x4, 57,000 miles, quad cab, short bed. Whenever I take my foot off the brakes, there is usually a bit of a rough release. The front pads have been recently replaced and the rear shoes were recently inspected and adjusted at the dealer's shop. Any clue as to what could be causing the rough release would be appreciated. It doesn't do it every time, but more times than not. Thanks