I`ve noticed something similar i play Reggae Guitar mainly so it`s barre chords and my index finger is curling badly across my middle finger and when playing can see the bend in the finger i`ve just put it down to years of playing and the finger has just grown accustomed to that position,When i play finger style Folk the index finger gets in the way and dampens strings it never used to,I don`t know how often you play or what the condition is(but if you`re feeling tenderness could be R.S.I) i just put it down to it`s used to it.You mentioned orienting your hand i did a little and it helped.Don`t know if you can agree with any of that?