Aperture RAW question
Hi Jacob. I think you're just seeing the camera previews (which will have any Picture Control you've chosen applied).
Apple changed the way previews are generated from version 3.3, preferring the camera's embedded preview to speed up browsing and import. At some point this preview will be swapped out for either Aperture's own preview or Aperture's decode of the raw file.
There's no auto enhancement taking place and you see the same behaviour in Lightroom when it swaps from the camera preview to the decoded raw file.
There's a better explanation of the process here in the Fast Browsing Camera Previews section.