Aperture 3.4.3 and Nikon D600 turning loaded thumbs dark

I only use RAW files and recently images loaded in preview look normal when loaded but when clicked to open for review and work they process at least 1 stop too dark?

This tends to effect the highlights when adjusted to correct exposure etc.

I notice this seems a common developement similar to what happened with some Canon cameras.

Any ideas what is going on?

This used to never happen before and I have used Aperture since its launch on day one.

I notice some feedback re RAW interrpretations for software but....