Both Blues/Jazz and Balkan music use a note that in the Middle Ages used to be called "the Devil's note", simply because it wasn't belonging to a strictly formalized theoretical hierarchy.
Musically, it's the sharp 4th of flat 5th.
In Jazz and Blues, the 'blue note' is is typically a connecting note between the fourth and fifth step , mainly known as 5- or diminished (sometimes flat) fifth.
In the music of Greek and the Balkans, the same note is usually a sharp fourth (4+) and it creates a tension as it jumps from a minor third step.
In this composition, both perspectives are used.