Yoast WordPress SEO (Page Titles & Blog Titles)

I just installed the Yoast WordPress SEO plugin and a really wacky bug has cropped up. For some odd reason all “pages” and “posts” are grabbing the title tag of the very first blog post I published.

The title section of my header.php file looks like this:

<title><?php wp_title(”); ?></title>

And the “Force rewrite titles” has been checked.

Has anyone experienced this before? Any help would be appreciated!