A question about left hand position: I only play a four string fretless, and I usually keep my thumb in the middle of the neck. But when i'm playing on the E and A strings, especially on lower frets, i have my wrist below the neck, fingers pointing up. But when playing the D and G strings, espicially in the middle of the neck, my wrist comes behind the neck, and my fingers become more paralell with the neck. Is this normal technique? It does cause some pain/discomfort in my wrist, but it seems like a natural way to play.