Yes so this happened back in early June. And yes, I mean rear locker.
I pulled my diff shortly after a 1000+ mile trip, and there was nothing that looked too bad inside. I have a link over at Rubicon Owners Forum hoping that someone has experienced this failure mode before. http://www.rubiconownersforum.com/forums/20-tj-drivetrain-horsepower/91858-03-rubicon-locker-problems.html
I have wheeled 2 times since then, and used this as my daily driver for the past 2 months. No bad noises, but I am going to pull the covers off again this weekend.
Now neither of my lockers work. Both pumps work and hold pressure, but something is wrong. I am going to pull the covers and jack the jeep up this weekend to verify that the diaphragm is moving.