From a safety standpoint, it's nothing to worry about. Mine do too (at times). I think a slight warping of the rotor causes it to rub against the pads and the rubbing causes mine to "ting". Sometime, I'll pull the levers and release real quick (snapping action), it'll go away. If you want to try a few cheap easy things, make sure the rotor screws are tight (and evenly torqued), and clean the rotor with rubbing alcohol. If you have adjustable pads, perhaps dial them out a tad.