if you bend a pipe do you hear creaking? no.... that was is goin on its bending, bending and bending and teh internal structure flaws like air bubles and cracks, are propogated to the surface until the material fails... 2nd year engineering materials class, university of ottawa.
why would you hear creaking? it didnt break at the seem where the steerer is pressed and fuzed to the crown, it sheared where the internal taper starts. so it happened due to fatigue in the material and small imperfections inside the mater, such as internal material cracks (cracks that are found at atomic level).. probly just a lemon, or a bad section of tubing used for the steerer.
I would have to agree with summit...probably a bad batch of tubing. QA/QC in Taiwan isn't that great, coupled with multiple vendors being used to build one assembly.
I drove my DJ into a parking garage the other night. Argyle 409 is fine. Rotates in the head-tube perfectly. Dented the trunk of my Volvo pretty good though... The Thule rack failed well too. A couple of the replaceable parts are shot, but the main tray and the rack itself is fine, along with the bike. Made a damn loud noise though. Thought I was losing the bottom of the car...until I realized that there was a bike on top of the car.