I received my new 5D2 from B&H last week, which I bought specifically for low light use. However, I've noticed a strange banding pattern emanating from blown highlights against a plain background (examples attached, ISO 6400). It doesn't look like regular banding or sensor bloom, so I'm not exactly sure what to call it. Dark horizontal streaking, as it only occurs horizontally? I've never experienced this phenomena on my 7D (or any other camera I've owned), even at ISO 12800. Is this phenomena normal or should I send my camera back? Thanks for the advice!