The image is only 781px wide – http://streamline.flywheelsites.com/wp-content/uploads/2013/07/Streamline-webhead-781×280-v2.jpg I took this directly from the slider.
You may just need to reupload it in the featured image area, and make sure that WP uploads the full size of the image. Sometimes WP will shrink or crop it, so that should definitely fix it by reuploading it.
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