I noticed some unexpected behavior with macchanger. If I assign a random mac, then associate with a wireless network, then disconnect from that wireless network, my mac address gets reverted back to the permanent address. I would expect that even after disassociating, the mac address would remain the random address.

Steps to reproduce:
ifconfig wlan0 down
macchanger -r wlan0
ifconfig wlan0 up
ifconfig (confirm mac address is newly assigned random mac address)
Now associate with a wireless network. I googled something while I was on the network but I don't suspect that traffic over the interface matters. Now disassociate from the wireless network.

The mac address is back to the permanent address. I would expect the mac address not to have been changed. I suspect that the traffic while associated with the wireless network is using the spoofed random mac address because if you hit ifconfig while associated you do see the random mac. I haven't been able to do an airodump-ng on that traffic because I only have one kali instance and I can't very well monitor and associate with a network at the same time.

Does anyone know why this occurs? Is there a good reason that I am overlooking?