Lena has learned that smooches at the door mean that we’re leaving, and she will say "bah-bye!" and wave after smooches. Any attempt to get more smooches or to say bye again will just get a firmer "bah-bye!" from Lena.
I can almost see it in her head: "You gave me smooches and said bye! I am considering you gone! Go! Bah-Bye! Do not drag this out!"
Last night, I put her to bed, tried to give her a good night smooches, and she looked at me and said, "bah-bye!" I started to go through the end of the song, but she was done. "Bah bye. Bah-bye!" She apparently just wanted to play in her crib and talk (with finger pointing) to her dog and cow stuffed animals (kept in different corners until some kind of difference between the two was mediated by Lena.)