This might relate to other DBA front rotors for the WRX besides just the 4000 series.
The problem is with the rotors scraping the inside tabs on the clips that hold the pads at the top and bottom of the caliper bracket. As well as the rotors scraping the actual caliper bracket. I wish I had taken pictures of this when I had mine off but I will describe it the best I can. The way I found the problem was when turning I would get an awefull grinding noise, I thought at first it was just noisey pads so I bought a different brand pad but the problem was still there. I then noticed a groove starting to form on the rotor. I looked at this horible groove in relation to the caliper and bracket and found the cause of the problem as I described above.
I then proceded to put my OEM rotors on and I had no more issues with scraping or noise. Oddly enough I met another WRX owner who had some DBA rotors and I noticed the exact same problem on his rotors, a groove maybe 3-5mm wide near the outside portion of the rotor, maybe about 8-10 mm from the outside edge of the rotor.
I wanted to post this because I wanted to see if their were other people that had this issue, if it happened to two people so close its bound to have happened to others. Also his rotors are about 1 year old now, mine were brand new, so its not just a certain batch of bad rotors I don't think.
Also I know DBA stops by these fourms oftern, maybe they can clue us into whats going on and any possible fixes. I don't want to see my 260 dollars wasted, and I really loved the performance of these rotors.