I was told by someone a long time ago that every quilt has at least one mistake. Well honey, you found it!
It's a beautiful quilt and I would not think twice about mentioning it to anyone!
Anytime I make a mistake, I say nothing. If anyone points it out, (which is rather rude of them anyway!) I chuckle and tell them that little folk lure about every quilt having a mistake in it, and then I say to them, 'now you have found this quilts mistake, you have a very sharp eye!'