Pretty sure, at least on this track, anyway. I played it and came up with no D flats... and then to be sure, I sustained the note on my keyboard (using my toe
) while playing the second half of the track, and came up with only one chord where it would fit.
Either way, the piece seems to center around C. I suppose maybe it could be in f-minor and start and end on the fifth, and then the D-natural in the melody could be explained as that second-to-last chord being a secondary dominant? V6/V?
Or perhaps I'm just going slightly mad, because that seems a little awkward-sounding to me.
EDIT: Just looked up "borrowed chords" in my theory book, and that idea makes a lot more sense to me, since the piece has characteristics of both C major and minor.