Sporadic shaking on the highway. After a restart it runs round again.

Estimated community Our RR Sport from 2010 is jogging sporadically on the highway. It is filled by the rear axle/brake (right). When I stop and park the car, wait two seconds and start again everything is back to normal. That happened several times now. I was at the garage, they did a test drive, it ran impeccable. The memory was read out and found nothing. Does anyone have any idea what this could be about? Ev. a brake that (electronically) no longer dissolves? Thank you in advance for the help & good ride, Driva