Very interesting. Just tried it here too.
In Lightroom I was able to "Reset" the crop and get to the original 4:3 in the RAW file. Lightroom displayed that the RAW had been cropped and showed the crop on-screen when in the Develop module. I was able to reset/remove the crop. (LR5.6 on Mavericks, E-M10).
I generally never shoot cropped since I hate throwing away image data, but it now appears I can do so while shooting R+J and have the ability to get jpg out of camera and still go back to an uncropped "digital negative" if needed.