More stainless info here:

http://www.ssina.com/faq/index.html#3

Check the FAQ about rusting. I'm guessing crank bros. may have got some poor quality stainless that was used in those pedals. Regardless of where you got the pedals, you should pursue it with them and send them your side by side pics as I'm sure they have a vested interest in product quality.

BTW, I have 3 sets of stainless Crank Bros. pedals and have never had any rusting issues on any of them (and hope I never do). Good luck.