Well, when someone says they had trouble with a song it's a dick thing to come along and say how easy you felt it was and how you did really well on it.
It's not quite the same, but I think of it as being like a guy picks up a girl he think he wouldn't normally be able to pull, takes her home, has a bit of trouble getting it up, but it works out in the end and he's glad to have had the chance. A few days later his friend comments on this by saying "Yeah, but with me she wasn't faking." It's just not the classy thing to do.
But enough about your mom....