I wonder if John ever hummed Paul's tune (Too Many People) to himself even though it was an attack upon him. "That was your first mistake. You had your lucky break. Now what can be done for you? She's waiting for me."
The song is just so good and so musical. You can't help but sing it all day long once you've heard it (at least that's how it affects me).
Could it have had that same effect on John even though he hated Paul for the lyrics?