I agree. "Filler" implies unnecessary story used to fill up empty space. This episode was not filler. Even the reviewer discusses many important occurrences in the episode.
In my opinion, "filler" and "jumped the shark" are so overused on the internet that they have become meaningless.

I thought the same thing. Looking closer, I don't think Sara's hair had braids. It was just a pony tail with a lot of teased volume.