It sounds like you have pre-conditioning turned on. That's a sub-feature of "scheduled departure", so if you have set to have your charging completed by, say, 6AM, and you have pre-conditioning on as well, it will charge your car and have it conditioned to your preferred temperature by the time you're scheduled to leave in the morning.
I don't want to be one of "those" people that tells you to read the manual.... but seriously, if you have an hour to kill, read through the manual and learn about all the things the car does. You might just find a cool feature that really helps you. At the very least, you'll understand what is happening when you find your car running its climate control when no one is around.