"I Feel Fine"

A couple days ago, I figured out the solo in "I Feel Fine."  The next day (yester-day), I was thinking about the song again and noticed an interesting feature.  In the lines "I'm so glad that she's my little girl / She's so glad; she's tellin' all the world," the first halves ("I'm so glad" and "She's so glad") are sung by multiple voices.  Because there are more voices, there's a sense of the degree of those "so"s.