Unfortunately I couldn't say that I inspected the die before use. I simply set it up and without a second thought. But I highly doubt it was a manufacture fault.
I think it's best bet to say I've managed to get some dirty brass up there and scratched it somehow.
After a couple of resizes brass builds up in the cavity and starts scratching cases again. I'll be heading to my LGS this morning and getting a new set.
Just a heads up for everyone though, inspect your dies before use
This brings another question to mind though; Isn't this sort of thing likely to happen for people who resize and decap before tumble cleaning?
I'm pretty new to reloading, and I've been tumble cleaning before resizing. This leaves the primer in the case and doesn't clean the primer pocket of course.
But I was trying to avoid this sort of thing from occurring.
I might try the other way round and see how I go.