I try to give credit where credit it due.
12 of the 61 posts to this thread report encountering a Sebenza with an off-center blade, so it seems that it happens from time to time.
So, about six weeks ago, I wrote to CRK, related my recent experience, and asked if I should expect a Sebenza blade to be centered, and I asked if could return it for adjustment or a refund if it was not centered. CRK has not responded, but I found an internet dealer with stock that was willing to inspect the knife before shipping it to me and agreed to let me return the knife if it didn't meet my expectations, so I ordered a replacement from them that's proved to be satisfactory.