When playing an open string, I notice that as the note decays it goes sharp. This is most noticeable on the G and D. Also, the octave harmonic on these stings is sharp compared to the open note. The bridge feet visually appear to be centered to the notch, but I haven't measured. Do I lengthen the string (move the bridge down) to get consistent pitch? Is this something I can safely do at home? Thanks.