yeah, sometime ooc. ive reviewd my years worth of photos and i do now see similar effect, though not very often, with every cam i used--gxr, x100, epl5 etc.
also, ive been much more careful about taking raw + jpeg with my rx1, and i actually see a pretty big quality difference ooc in many situations--ones that dont involve this particular effect. i personally have never seen such a raw vs jpeg disparity in seemingly benign or 'somewhat' challenging situatios with any other cam ive used. just the other day, shooting into overcast skies with sun clouded 'bright' spots, my jpeg image had some serious concentric 'blobs' rendering it useless, while the raw was perfect.
so, im coming to the conclusion these are jpeg artifacts. im no longer worried about it being a 'camera' issue because i can find similar in other cams. now i just shoot raw + jpeg and go through a couple extra steps to get files to what i consider a manageable size.
i will update if my raw shots come up grubby.