Certainly that example, yes, but even more broadly than that. The difference between a 9.9 and 9.8 is so miniscule as to be almost undetectable. People spending tens of thousands of dollars on 9.9s, I believe, are greatly underestimating how much a comic gets bounced around, even inside of a slab, particularly during the shipping process. I suspect that the vast majority of these copies, if they were to ever be regraded, would end up 9.8s or even 9.6s.
For those who know the Signature Series world, it's generally advised to not crack open 9.8s for signature events due to how often grades come back lower. I won't even send in 9.8s in old generation slabs to upgrade to newer slabs since CGC reserves the right to inspect and regrade books sent for reholders.
The grade on the label is merely a snapshot in time.