I think, in effect, yes, it was 5-4.
The Mississippi law in question was upheld 6-3, but four justices implacably opposed overturning the precedents in question.
The Chief Justice apparently saw a way to narrow Roe and Casey to bring about the desired result (preserving the validity of the Mississippi law), but could not persuade his five colleagues that his reasoning was sound or viable, so was left with a concurring opinion (agreeing that the Misdissippi law should be upheld, but not on the reasons why) and nobody to join him in that concurring opinion (the other justices (united in dissent) agreeing with him that Roe and Casey should be preserved, but, unlike him, ALSO believing that the Mississippi law should be struck down).
Thank you for the explanation. I haven’t followed closely, but I knew many FReepers would.