When someone leaves what seems like a nice, innocent comment but is actually a sneaky way of congratulating themselves. Usually for something that doesn't deserve congratulations.
This comment left on a soundtrack that was used in the Umbrella Academy series:
Sneak self-congratulation compliment: "Thank you umbrella academy for reintroducing this to the next generation."

It seems like an innocent comment, but is actually a way for the commenter to congratulate themselves for knowing the soundtrack before it was in the series. The commenter also believes that they are better than the people who are just now discovering it, and that he/she should get a reward for knowing the song for a longer period of time.
by TaiChiTony July 11, 2019