Hi Radu,
Found it: spread the word!
It was confirmed on Facebook’s bug platform that they had made some changes to the the default settings for new Apps and now Strict Mode is automatically enabled for the oAuth settings. Strict mode means that when using Facebook login to connect your application or website to the App, the oAuth redirect URL has to be explicitly set, where as before it didn’t.
Under Client oAuth settings, where it says Use Strict Mode for Redirect URIs make sure it’s set to No and that your site URL is in the Valid OAuth redirect URIs box. Then the hit save.
It's working now -> me happy.
grtz
g