Looks good to me, though you may want to enter something in the post/page Excerpt for the OG description. Odd that there’s no image height listed. If you turn on debug mode, I can have a look at that.
<!-- NextGEN Facebook Open Graph (NGFB) meta tags BEGIN -->
<link rel="author" href="https://www.randpaulreview.com/author/libertyninja/" />
<meta name="description" content="[Show as slideshow] " />
<meta property="article:author" content="https://www.randpaulreview.com/author/libertyninja/" />
<meta property="article:modified_time" content="2013-05-03T16:43:00+00:00" />
<meta property="article:published_time" content="2012-04-09T15:46:59+00:00" />
<meta property="og:description" content="[Show as slideshow] " />
<!-- og:image:1 --><meta property="og:image" content="https://www.randpaulreview.com/wp-content/gallery/cache/250__300x300_clhirzwj.png" />
<!-- og:image:1 --><meta property="og:image:width" content="300" />
<meta property="og:site_name" content="Rand Paul Review" />
<meta property="og:title" content="Rand Paul Review | LibertyGallery" />
<meta property="og:type" content="article" />
<meta property="og:url" content="https://www.randpaulreview.com/libertygallery/?album=1&gallery=4" />
<!-- NextGEN Facebook Open Graph (NGFB) meta tags END -->
From the FAQ:
Q. How does NGFB find images to include in the Open Graph meta tags?
A. The images used in the Open Graph meta property tags for Posts and Pages are chosen in this sequence:
1. A featured or attached image from a NextGEN Gallery or WordPress Media Library.
2. A preview image from a NextGEN Gallery [nggalbum] or [nggallery] shortcode.
3. Image(s) from NextGEN Gallery [singlepic], [nggallery] or [nggtags] shortcodes.
4. Image(s) from <img/> HTML tags in the Post or Page content text.
5. A default image defined in the NGFB plugin settings.
js.