I love you bro!
Somehow between my guy friends, we say that in a joking way, with exaggerated voice as if we are kidding... except we are also being sincere. kind of too embarrassing to do in a straightforward way.
my four year old son will also tell both my wife and me this many times per day .... everyday. I think he will grow out of that, but I think he does say it when he is thinking it.... and I am happy that he seems to be thinking it pretty often :-)