then it means that wireless is being disconnected or removed from AP by AP due to reason X or Y or Z. this could happen due to many reasons. AP support file may throw some insights into why this may happening plus some background info from you on the site where AP is used, type of devices in use, type of application, potential interference source etc
Not to be alarmed. These messages began appearing in 9.6 and 9.7 ZD firmware
and indicate that a client has roamed away. These msgs are most often AP clean up, to clear sessions of users who have left the AP/BSSID.