In "Glory Days", retired superhero Lift-Off attends a reunion of the members of his super-team, hoping to meet fellow member Belle-Air, whom he always had a crush on. At the end of the tale, they do meet ... and he thinks, "She hasn't changed a bit". We see that she has ... but it's pretty clear that he doesn't. Neither does she. And they dance on air.
Made all the more heartwarming by the last entry in the timeline in the first trade paperback. They got married a few months later.
Also heartwarming is the end of the story "This'll Be The Day", where patriotic American Pi, starting to despair about the way she fails to connect to the people she wants to protect and inspire, meets a young boy who, thanks to his own horrific background, knows exactly where she's coming from when she talks about America being the land of opportunity.
"Time Of Their Lives". Particularly the twist ending.