Honda Repair: 2007 Honda Civic brakes, honda oem, oem pads

Question
I just completed replacing the front brake pads on my 2007 Civic.  I have performed this procedure approx. 20-30 times over the years on a variety of vehicles, but this is the first time on this car.  My Civic has only 30k miles (got it at 5k) so this is the first replacement and all parts are relatively clean and in good shape.  I used Honda OEM pads, and had the rotors turned.  Reassembled without problems.  Went out to test the brakes seemed fine at first but then with hard braking there is a noisy chatter with slight vibration coming from (I think) the front left area.  Metallic chatter/grinding.  Not every hard brake but every couple times.  Took both wheels off, lifted up calipers, checked every part, bolt, pad, shim, etc.  Everything fine and in place. Every thing tight. Reassembled.  Another test drive.  No change, same chatter/grinding.  Any ideas?  Input appreciated.

Answer
The first thing I would check is that there is nothing that is hitting against the dust shield. Sometimes debris can get stuck between the dust cover and the brake rotor.
The other thing that you might check is that there isn't anything between the brake pad and the brake disc. Sometimes debris can get caught in between the two.
That is where I would start. I would also compare all of the new parts to the old parts to see if any of them are different. Also be sure that you replaced all of the old parts with new. Sometimes people don't replace things like shims and that can cause problems.