Fillers happen in just about any anime I've ever seen. Sometimes the filler doesn't happen as a full episode, and sometimes the episode just goes totally out of the way to show itself as being filler (see: Nadesico). Here, you can tell from the title "Side Adventure" that what happened in the episode has nothing to do with the main story arc. I'm hoping to see Naruto meet back up with Sasuke and Sakura and go out on a mission. They just came out with a movie and a double episode, give them a break, eh?