Yeah, that doesn't look right. Is it only on that one side or does it run all the way under and out the other side? How long have you had them?
Can you send them back? I'd send them a picture or describe what's happening and see if they'll fix it or replace it.
My Aldens both have what you called a fault. I am almost positive that they had it when I first got them. I've had them for a little over a year and a half and it hasn't caused any problems. How long have you had your pair? I'd guess that it is just part of the design of the 405s. I wouldn't worry about it, but if you are I'd recommend taking them to a local cobbler, who could tell you if they are in need of repair and probably do any repairs needed for a reasonable cost.
Shanghai, this would concern me. This is the sole, and this is a solid piece. From what I'm able to see here, it's cracked all the way through the boot, so the entire boot is now flexing through this crack.
I just looked at my boots also. They don't that cut or what ever it is. After studying them I think your problem was caused but the sewing machine. It looks like they didn't have the boot lined up right and it cut a slit down the side of the heel. Its definitely a flaw, but I don't know how serious it is.