A magician's victory lap and also the Petty final say.  The moment of 'I told you so.' It might look like pure ego from the outside but that's isn't whole truth. It's a ritual of completion. Like a bow to the audience. A seal on the letter.
There's something that could be read as petty in these finishing moves. But pettiness implies judgment and magic demands flare, beyond that it's just how it works.