Abnormal Noise

I have a 2012 III Prius with 63,000 miles. Last evening on our way home I noticed a rubbing noise after stopping on the freeway exit ramp and then turning left. My first thought was that I picked up some debris and it was dragging on the highway. I stopped right away at a gas station and found nothing dragging under the car. The noise stopped when not moving with the engine running. We continued on our way and the noise went away after a couple miles. It occurred again after another left hand turn into our driveway and a stop. This time I stopped part way up the driveway and backed up a short distance after which the noise stopped when going forward again.

My first thought is that I may have a brake caliper sticking, but I don't know if it has anything to do with turning left and I don't know what other brake hardware is included with the regenerative brakes. I have no warning lights appearing when this occurs. I couldn't really identify where the noise was coming from other than in the front. My wife sitting in the passenger seat, thought it was coming from the left. Anyone have any suggestions on what this may be and what the fix involves? I'd like to have an idea what the problem is before taking into a dealer.

Ron.