Most likely, they had one or two of the drives in stock because they were previously RMA'ed for some reason or another. So whoever bought the drive(s), make sure it is not a lemon.
A couple of months ago, I bought a 4x Plextor SCSI CD-ROM from them. The unit was seriously defective. When I RMA'ed it, I asked to get another of the same unit, but they were out of stock, so I took credit. About two weeks later, they had the 4x Plextor SCSI CD-ROM back in stock only to go out of stock in a day. I believe someone had bought the crap drive that I had returned. So buyer beware.