When his car was stolen, it was immediately returned when they realized whose it was, with a fresh coat of wax and a note of apology attached. Possibly.
While on a packed subway going home, someone recognized him and everyone started to sing his theme song.
The crowning CMOH, though, would have to be the story this former employee relates. Many of the men working for Mr. Rogers would make fun of him behind his back for being too soft and the like - but in private, they would sneak into where he was rehearsing and privately ask for personal advice ranging from impotence to marital troubles... all while talking to his puppets, at that. On top of that, he never showed any sign of having had those conversations with them, as a way to respect their privacy.
Here's a whole list of CMOHs for Mr. Rogers. This is guaranteed to make you feel a little bit better about humanity.
Every. Freaking. Episode.
Let's just be honest here... the man's entire life is one of these.
In this article for Guideposts, Mr. Rogers explains the origins of his Catch Phrase, "You made this day a special day just by being yourself." His grandfather said it to him word-for-word when he was eight, and Fred remembered it all his life. So when he got a job in children's TV, he wanted "to offer children the same kind of reassurance, encouragement and sense of self-worth." I'd say he succeeded.
Lady Aberlin's entire relationship with Daniel.
A story widely told is that a fundamentalist priest/pastor/whatever called on Mr. Rogers to castigate a nearby group of homosexuals. Without missing a beat, Rogers turned to said people and said "God loves you just the way you are."
He was an ordained Presbyterian minister (although he didn't preach—after his ordination, he was charged with continuing his television work) and belonged to a More Light congregation, a movement within the church dedicated to greater inclusion and participation of LGBT persons.
Fred Rogers wasn't particularly known to like parodies of his program. But he liked Eddie Murphy's parody so much that he even visited him on the set of Saturday Night Live, to tell him that he liked Murphy's parody.
A minor one but anyone who has browsed the internet will tell you that the comments section of almost anything is ripe for arguments, insults, bizarre logic, and attracts many terrible elements including threats. Yet in the video where Fox commentators try to make Mr Rogers seem like he was bad influence for children, almost everyone is united in defending him and saying what a positive impact he had on their lives. Mr Rogers: The man so nice and beloved he even united the internet.
His visit to the set of The Incredible Hulk was heartwarming. To add bonus points Fred Rogers shaking hands with Lou Ferrigno in full hulk make up. To an adult watching this show it's no big deal since it's two actors shaking hands and one is dressed up at the time. But to any kid watching this Rerun or no Rerun, it's Mister Rogers and The Hulk Shaking hands, Rogers showing no fear of him whatsoever.
This Cracked article as well as the comments attached to it demonstrate the same love Mr Rogers always would have wanted for all of us.
A comment in this reddit thread about why Mr. Rogers always announced out loud that he was feeding his fish (because he got a letter from a blind girl who worried they weren't being fed when she didn't hear him say it).
It's funny how Mr. Rogers's words end up carrying through to your adulthood. I was once had a co-worker who was being a total jerk to everyone. When he turned on me, I let him have it! I said, "You are not acting like the person Mr. Rogers knew you could be." He stood there flat-footed in shock. .... "Damn, that was harsh man." About 30 minutes later he personally apologized to each person, one by one.
True or not, the fact that it's totally believable just indicates how much everyone loved Mr. Rogers.