Just contacted CGC about my 19 books that arrived with the defect. Paraphrased, but I'm typing this right after the call, to be as accurate as possible with no attempt to mischaracterize the answers I received.
Q: My 19 books have a wierd indentation defect on the back of the book, others have apparently been reporting the same issue, are you aware of this?
A: Yes, it is a problem with the manufacturer of the inner wells, we have contacted them and we are awaiting a response.
Q: What can be done for my books that already have the defect.
A: Nothing, because the defect does not impact your books themselves.
Q: Why are these cases making it through QC?
A: Because the books themselves are not damaged.
Q: Yes, but what if I sell one of these defective capsules and get a complaint, or hurt my feedback rating or buisiness in the process? (note I don't have a business, but it's a legit question)
A: The buyer can contact CGC and we will tell the same thing.
Well, there you have it. I'm taking a collector's strategic pause of sorts until CGC can restore quality standards to the pre-CGC case defect era. It would be good to nail down when the "O" defect manifested itself.
Minor grammar edit to Q2