"so..."

Zoe's new habit is to sit down, look at you and say "So...." usually followed by "How'd you sleep" or "How was your day"... this morning she sat down in the toy room, looked at me and said, "so...Mom! when some one says so, you are supposed to say 'so...' ".. of course at that point I couldn't do it with a straight face. Now she's made it part of a knock knock joke to crack me up.