Is it me or my whippet always looks kind of sad

Long story short i have a girly lady 9 months old whippet. I love her she is the laziest girl.
But i dont know if its the face or whatever but she constantly looks sad. I know when she is happy i can read it from her face - when we come home or when she is out playing and runnign with other dogs or when we are playing with her but by default she has this sad face when just lying around the house. Is it me or its the case or my dog is depressed.