2003 Ford Explorer a clicking noise in the front brakes

I replaced the pads and rotors (new) in June with app. 95,000miles. There is a clicking, metallic, sound now when I slow down. I can hit the brakes several times and each time I hear a metal to metal click/clink, not loud but clear from inside the car-the window is down.
It does not make this sound all the time, app. 75 to 85% of stops it does make the sound, and does not make it in reverse.
Any ideas on my problem? Does something need greased or cleaned? Do the lug bolts need tightened? Do I need to take everything apart, clean them and reassemble?
Thanks!