I'll be seriously surprised if it's not that. It felt somewhat forced script writing how nobody thought about it, considering they all knew Jiraiya was as much a book author as a ninja.
I'd imagine it could be something that helps Naruto against Sasuke's sharingan powers. If Sasuke indeed can override Kyuubi normally, it could be something that prevents that, or it could be a defense against sharingan genjutsu (since Naruto is far too stupid to be able to do anything against genjutsu of any level).
Anyway, I liked these eps despite the fact nothing much really happened action wise and much of it was Naruto emoing. However, the ways they brought him back from emoemoland didn't feel forced or artificial. Even the meeting with Kurenai wasn't sugary but rather nonchalant like you'd assume something like that to happen in reality.
What was missing here, in continuation to Iruka and Shikamaru's lessons, was somebody to kick Naruto's ass to get him back to training. Maybe it'll happen in the next ep or the one after it.