Its possible that they could be caused by the white points from the HDRI image causing blowouts in your final render (after all, you've got a lot of reflectivity going on there).
Couple of things to try:
(1) Slightly blur your HDRI image (or use a 1-5% reflection blurring on your surfaces) to try and clear down these 1 pixel hotspots.
(2) Try darkening the HDR image with a plugin like HDRI expose to see if that stops the blowouts...
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