I have exactly the same issue: I have exactly one(!) declined comment flag, but I have no idea what comment it refers to, or why it was declined. Maybe it was a well-deserved declination, maybe I just hit the mouse at the wrong time and the moderators realized that, or maybe it was a legitimate use of the flag but the moderators made a judgment call and left the comment alone--who knows?
Who knows? That's the point. If the declined flag count is meant to be a useful feedback mechanism for users, I really think that it should be more informative.
I'm going to change this to a feature-request and see if we can make this statistic more useful to the SO community. What say you all?