Ring Motion Sensor set a false alarm after a battery check

The other night the home alarm was triggered by one of the motion sensors. We checked and there was nothing around, neither human beings nor animals. Looking at the even history there is something weird happening before the motion detection, the sensor did first a kind of battery check (batteries are few weeks old and charged) with the following steps: 1) Battery Is Ok 2) Battery Is Full 3) Motion Detected None of the other motion sensors have similar cycles in their history. Is this a unit defect? What to do?