Thanks to all for your opinions.
I knew up front that I could get a refund, my real question was whether I was being unreasonable in my expectations, some have said 'yes', some have said 'not really'...that's all I needed to know. I had not considered that this filler might not have been apparent until the final polishing and that's the type of thought I was looking for, questions I hadn't thought to ask.
The vendor and I have come to an agreement and that will end the matter for me. He doesn't feel the need to 'inspect with a microscope' (his words) each knife that he sells; I feel that this defect was quite obvious without one, agree to disagree.
I'm going to lock the thread as I feel it has served its limited purpose.
Thanks,
Russel