Was your image originally big? I just tried a smaller image but something I noticed is increasing the size to 769px in width, so something is definitely wrong somewhere. I am looking into this and to find out what is forcing the larger image.
UPDATE: Actually, I think I found the issue. I am working on a fix.
This might take me a few hours because it looks like I need to change how the featured image is done. I am thinking there is something with WP 4.0 that has changed how images function because this never happened before.
I think I have a solution to this problem which I can send you an update version (test version) that you can try. Any feedback on how it works out for you will help determine if the update is ready for release. Contact me from HERE for a copy of the changes I made.
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