I feel like I've known for years intuitively that the G string is a little weird... usually feels sharp, especially when playing E-based power chords. Is that just because the third is played on that string in these chords? I guess I have no idea why it's the hardest string to keep in tune from chord to chord. This has been bugging me for a bit. I'm sure there's a good answer, but I just don't know it. What is it?