by ben reynolds.
I would say this is a browser issue. I am not a Safari user, but I would look into how to remove Google cookies from the browser.
When you reopen Moodle, it goes looking for Google cookies, finds the most recent, which is the wrong one, and starts the trouble.
I've run into this kind of conflict using FF between a school Google login and my personal Google login. In no case should both be opened inside the same browser.