My truck has been doing it lately too, I was meaning on posted a question, but keep forgetting about it. Mine sounds like it's the driver side, I replaced the hub about 2-3 months ago, so I doubt that.

 

My truck does the same thing. I brought it to a shop and they told me that the backlash in the rear was bad, so they replaced the posi (I have an extended warranty). The problem was still there, and I had showed them. They said, "Sounds like a brake pad hitting the rotor" because i noticed it when in reverse backing out of a parking space and when i pushed down on the brakes OR if I let off the brakes.

It doesn't do it all the time as well.

I had the left side hub bearings replaced. Still does it. I think it might be a sticky caliper piston (i have 2 piston calipers) on the right side. the right side has a lot of brake dust, more than the left.

If it doesn't break down, I don't get worried. However, I have an extended warranty with free roadside assistance, so I have that peace of mind.

BTW, I noticed a banging noise under braking...turned out it was a used oil filter slamming the bed that i forgot to take out of my bed when bringing my oil to autozone!!!

 

i am getting a clicking sound from both sides of mine. had my oldest son stand out side to try and tell where it was coming from. he described that it sounded like it was right behind the wheel on both sides. the wheel bearings are 2 years old. thinking its time for the warrenty to be cashed in. just did the axle u-joints and the ball joints so i am pretty sure it isnt them. so time to call napa. i should have just changed the wheel bearings(hub assemibly) at the same time, oh well.