'Random' Algorithm of iPod Nano 4th Gen. Onwards.

I'd like to make an observation regarding the 'shuffle' or 'random' feature of the iPod Nano, from 4th Generation onwards.
I listen to mine in 'Shuffle' mode most of the time and I've noticed that the music played is dictated by either the rhythm of opening bars of the music, or by the way the notes fall. Tunes with similar opening music are grouped next to one another, in other words.

Is there anything in this? I realise that 'random' can, and might, include all the tunes in correct alphabetical order, for example, as this is a mathematical probability. But it seems that more often than statistics would suggest, the aforementioned observation about 'shuffle tune order' being dictated by the music and rhythm of the song introduction holds true.

Is there anything in this?