This is a neat little trick that you hear from time to time at the beginning of songs. The song starts out in 6/8, with an eighth note pulse implied by the only parts you can hear. However, when the drums come, they imply a different pulse and a new tempo, and that changes your whole rhythmic perception of the song. The drums play out in 4/4, but the original rhythm section continues on at its original speed, which creates a metric modulation. The former pulse of the song (the rhythm of the guitar), now sounds off as sextuplets in relationship to the drums.
Music Morsels are musical fragments, collected and analyzed.