Action
He understands the need to cut loose and flex the powers a little upon release of the power-limiting ball and chain. Adrien himself did almost the same thing, it also makes getting acquainted with the facility as a whole so much easier leaping from roof to roof.
He also hasn't met another actual superhero other than Ladybug besides himself before today. He tends to get rather enamored with girls with these sort of powers, but Kara's way out of his league.
And age bracket.
His baton helps him reach about wherever he wants in terms of height, a perk of the costume that he has it here. Actually, a perk that he has any of the costume in general. He'd not be able to do anything if not for having the ring and Plagg.
Still, he wants to seek out the female superhero so he uses his baton to literally pole vault himself into the sky to reach her.
It will only be a moment, just enough to say hello before he has to drop back down again, but he'll be back in about 3 seconds.