Xbee 3 rand;ly returns 0x40 upon AT Command AI where 00 is expexted

I am using 2 x Xbee3 in API with escape mode. Each Xbee module is connected to an Arduino Uno board. In the sketch I am using the arduino Xbee.h library to check the status of the remote node, using the AT command AI. While most of the time the return value is 0x00 (as expected), it sometimes reports 0x40 (“Secure Join - Successfully attached to network, waiting for new link key”). The check takes place every 2seconds and 0x40 is returned randomly, every 20/30sec. The 2 Xbee modules have Encryption disable (EE=0x00).

Are there any settings I should look into to get rid of these please ?

Thank you.

That is part of the Zigbee standard and can just be ignored if you are not using encryption.