I received an email entitled "Thank You for Sharing" from Bonvoy. The content stated that I shared 50K points from my account. I immediately checked and my points balance wasn't short 50K. Still. I still changed my password and then called Marriott Help Desk. Apparently, a systems upgrade was performed and emails associated with old transactions (I did share points about a year ago) were going out.
Just trying to prevent others from getting the adrenaline rush I just had! Happy that my account wasn't hacked.