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)?
Craig Walls
Spring Social Project Lead