Honda brake backing plates (splash guards) are quite tight fitting and tiny pieces of stone easily get trapped (happened to me three times in my CRZ). Try stop-starting going forward and then reverse for short distances to try and dislodge the stone. Failing that, take wheel off and wiggle the metal plate behind brakes to see if that frees the stone.
If it is a sticky caliper, the alloy will be very hot to touch after a drive (noticeably hotter than the other alloys) as the brake is effectively being constantly applied. Sticky caliper may also cause steering to drag a little.