I don't see that noise in my ISO 1600 either. Could your spot metering have metered for the white background, making everything too dark, then your software automatically adjusted it back up where it should be, thus creating the noise?
I agree with several others. Turn off that Spot Metering. Useful (for my purpose) in a scene were you have all blue sky and only a bird which is your focal point. It ignores the sky and grabs only the exposure on the subject up to 3% of the center of the image if my memory serves me correctly. Partial metering is roughly 9% at the center. Use these modes only when needed, not as an every day default. Note on this site: http://www.cambridgeincolour.com/tutorials/camera-metering.htm where the author states: "...the camera's light meter will incorrectly calculate under or over-exposure, respectively." Hence if the area is under exposed then you found your culprit. I'm also not a big fan of AWB when indoors without flash. I prefer a gray scale card and K WB mode to get those colors spot on.
PS I have the Blue Crane DVD's on the EOS 7D and they claim ALO (auto lighting optimizer) does increase noise. So I've turned that off and use it sparingly only when needed.
Hope this helps you.