M.C.
I think its part of the age. We have family sayings and gestures that mean 'i love you', so that when we are in public or around friends we can say the family saying or gesture and not embarass the kid.
Like a double wink,
2 thumbs up,
'behave cuz i won't be home for hours',
'don't break anything, i've already been to the hospital once this week', etc.