[link to original on tumblr]
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The song starts off with that piano riff, and that same riff is played in the bass part later. After that exchange, it's not fugal because it doesn't develop anymore - that phrase just stays in the bass for the rest of the song.
But that first part - the piano playing that phrase and then the bass playing that phrase with a different piano part on top of it, that's fugal.
Well, it is as long as my understanding of fugues is accurate.