hi i solved this problem. it occurs when an inserted image has a width property of 100%. Instead of defining it in the theme base.css, i chose to define it in the html style element of the blogs plugin view index instead. I also used "max-width" instead of just "width."
Originally I was hoping that instead of just text, the blogs newsfeed item can contain a preview image item from the blog post itself. and so the blognewsfeed item will not just contain a text preview but an image and text.