Wow--I love your colors!! Great job! I agree that it looks terrific as is! That said, if it bothers you that much--and it doesn't soften--and you don't want to show it--since the issue is in the corners, it wouldn't take too much to unstitch and turn. ;-) I vote for leaving it though.
I, too, had a wall hanging up for years--right over my husband's desk--before I noticed one block is turned wrong--something isn't right. Eh--good enough.