Just a guess, but it's possible (I guess?) that if your front mounts are worn, and not able to allow for a smooth movement, that it's allowing it to kinda of catch, and cause it. I would be surprised if it didn't clear up after you replace them.
Edit: Another thing you could try, is put the car on a jack stand on that side, remove your wheel, but jack up the control arm with a jack to put some pressure on the assembly and see what happens then (obviously don't jack it high enough to move it off the jack stand).
Last edited by CharlzO; 07-25-2013 at 08:45 PM.