I once worked with a group that made a raffle quilt. It was hanging in the front of a room full of people and low and behold the mistake in one of the blocks jumped out like a bolt of lightening. We very carefully ripped the area of the mistake. Fixed it by hand and requilted the area. It was tedious but we did fix it. However, if it doesn't bother you just leave it. Some cultures believe that you should always have an imperfection in your project so the "Gods" will not be mad. LOL.