I made some minor adjustments after i put mine on... It affects the way the string deforms when the arrow is released, so it would make sense that youd have to retune.

Take a rubberband between two fingers and "shoot" it as if it were a bow, watch how the band moves back and forth. Do it again w/ another finger bout 1/3 of the way from the bottom... Has the same pattern of deformation, just in twosmaller bandwithds... (I got bored at work yesterday, and have rubberbands laying all over