Quote from kekpew
Naruto has had the Kyuubi inside him his whole life and hes an Uzumaki pretty sure that reason and the usual bullshit where he just magically learns the exact same stuff his father could do
Well, yeah. Though this isn't the first time he's given away his chakra though (he saved Gaara). I'd also add that his Sage mode training probably helped. It made him a sensor-type, which can't hurt his chances of figuring it out.
I still want to see him use chakra chains...lol.
Edit: On an unrelated note, does anyone else think the kyuubi looked cooler when he was evil?