Sorry Tartan it would drive me made if I didn't do something at this stage. If I saw it later in the quilt it wouldn't bother me.
It will only take 5 mins to alter.

As the others have said, only you can tell if it's going to annoy you. What I do now is carry on with the rest of the project and if the offending piece is still bothering me when it's time to put it together, I redo it.

Just recently I cut the wrong size of fabric on one small piece of a BOM and had to join pieces together. To redo it would have been a little pricey as well as a car journey, so I carried on and from even a foot away, you couldn't see the join, so I left it.

Another time I reversed 5 or more 2 1/2" squares on a twister quilt and noticed just before I started to cut them with the little square ruler. A royal pain unsewing, but couldn't bear to leave it as it was.

I am teaching my future grand daughter in law to make a quilt and when she sews something wrong she will ask me if she should pick it out or leave it. Since I am not a perfectionist I ask her if it will bother her later. I think your block looks fine like it is.

Back in the day when I was doing theatrical costumes (high school, college, and community theatre -- sometimes at the same time) I often used the "wrong" side of a fabric for the "right" side. The same goes with quilting, in my opinion, because the back side often has a muted color and/or texture which I really, really like. Once your top is quilted, I doubt that anyone but you will notice. They will be drawn to the wonderful pattern and colorful quilt which you have created. I, for one, would leave it exactly as it is. Perhaps you might turn another piece -- or two, or three, or more -- so it looks deliberate.

Because I am OCD-ish, and because it would be pretty easy at this point, I would get out my seam ripped and correct it, but if you know you can leave it as is and move on, I say go for it!

I would leave it as no one else would notice.

I would definitely leave it. I don't believe it is that noticeable. You are doing a gorgeous job on it, and I think it is going to be a beautiful quilt.

It would drive me crazy but, I would leave it anyway. Since I give away most of my quilts I wouldn't be able to see it.

Tartan, I have a quilting mentor that is always telling me I bought both sides of the fabric, to use it however I want to. No one will notice that it is an error, just keep it your secret

I've flipped fabric before, sometimes by accident and sometimes on purpose. If it was mine I'd just leave it in.