I see nothing out of sorts here. Sure, the constructor is being invoked, because you explicitly invoke it in the @Bean method for the ConnectController. Assuming that you're actually doing a Facebook connection, I see no apparent reason why the pre/postConnect methods wouldn't be invoked. I even matched up your code against the code in Spring Social Showcase (https://github.com/SpringSource/spri...ocial-showcase) and except for the details of each method, it looks the same.
A few starter questions: Did you try this with Spring Social Showcase? What versions of Spring Social (core/web/facebook) are you using? Are you certain that a connection is being created? What kind of server are you deploying this to (I ask, because I've seen trouble with interceptors working on Google App Engine)?
Spring Social Project Lead