She probably just smelled food from someone's open window.

Kidding. She might have some kind of psychic link, since when you first moved into your apartment, and you went to work that Monday while I stayed and unpacked things and set up shelves, she started lying near the door and started looking out the window a lot right before you got home. Even in a brand new environment she didn't know, her 'body clock' just seemed to know you would be arriving soon. Creepy. :lol