Blog title problem: No space between blog post title and blog name

I noticed that some of my blogs are having a spacing problem with the blog title, i.e. there is no space between the blog post title and blog name, that looks really bad.

It should be <blog post title> | <blog name>, but now it is <blog post title>|<blog name>

These blogs are using WordPress 3.5 and the default Twenty Twelve WordPress theme. Would that be possible that the All in One SEO Pack plugin screws up my blog title? So I deactivated the plugin, and the problem did go away. But I kind of want to keep that SEO plugin. Besides, my other blogs are doing fine without this blog title spacing problem. FYI, those blogs are using WordPress 3.5, All in One SEO Pack, and paid themes from ThemeForest. It looks like the Twenty Twelve Theme doesn’t work with All in One SEO Pack very well. So I tried to take a look at the theme’s functions.php file. Here is what I found out:

change line 185

add_filter( ‘wp_title’, ‘twentytwelve_wp_title’, 10, 2 );


// add_filter( ‘wp_title’, ‘twentytwelve_wp_title’, 10, 2 );

Now the blog title is working correctly. If possible, maybe it is a good idea to use paid themes, instead of free themes. Commercial WordPress themes most of the time do look better and with better features.