OK, this is really bizarre. I did a hard reset on my phone today to see if it would improve my battery life. After going through and setting everything back up, I noticed that Cortana, on her daily brief screen, was showing me an appointment that is in my wife's Google Calendar. I did not add her account to my phone, other than adding her in as a contact. I do have a Gmail account that her calendar is shared with, but I did not enter that account into my phone. My primary Hotmail account does not sync to my Gmail account. Gmail is set to forward emails to my Hotmail, but that's it. Has anyone else witnessed anything like this?