Apple ID verification code sent to wrong device

Had to login to iCloud on my Mac today, and it asked for a security code. Instead of sending the code to one of my trusted devices, the code went to my wife's iPad. Her iPad is not logged in anywhere using my iCloud ID, but she is part of my family sharing for iCloud Drive and iTunes.

After getting the code and logging in, I double-checked my trusted devices, and her iPad is not one of them. I have no idea why this would occur, even though we are currently on the same WiFi network, if her device is not "trusted" by my iCloud ID.

Sure, I can logout and login again, this seems to be the pat answer. But it seems really strange that this would happen in the first place. Any logical reason for this behavior?