I’m having a similar problem when posting the link to facebook for a post on my blog. In the past I would fill in that meta description tag, and facebook would see that and put that in as the description of the page when posting to facebook. I believe Google does something similar.
This is DEFINITELY a change with the lastest version. I just updated to the latest version of WordPress SEO this week and since then, I’ve seen this new behavior. We need to get this fixed ASAP as it’s going to affect SEO for our site.
