Our firstborn is moving out!

I'm having mixed feelings about my 21 year old son S moving out.  He didn't move far, but there is still a feeling of moving to a new stage in our lives.  I remember as a young adult that once I moved out, I NEVER wanted to move back in.  I hope as a parent, we have prepared him for the world and have taught him to be a productive member of society.  I am so proud of him.  He is well balanced and kind, with a great sense of responsibility and humor.  If he were a cartoon character, Linguine from Disney's Ratatouille would be it!
I did have to tell him that he couldn't take Landry with him when he moved out.  That little Boston terrier is staying put.