I don't think that this is a heattreat problem. The crack in my axe was clearly from forging, so I would imagine that here and there you might have a poorly forged out "fold", and if it happens to run through the edge, you have a problem. I agree with tarmix that it is probably not representative for the output of the company in general. As you, Noss, have shown, a GB without fault can be very tough.