Reading my way through the Mattie Winston series and was going to add the next book to my currently-reading list on Goodreads and discovered I....already read it?

So I thought, must be a glitch or something.  But no, there's a review?

WTF? I have no memory of having read it! Now, you may be saying to yourself "Well, you do read a lot..." but I usually remember books I enjoyed.  

I must be getting old.