An intruder did or didn't
and they don't know?
Kudos to them for accepting the worse case scenario and overhauling their systems.
So many systems belonging to large corps are compromised so often that I think it is obvious that ones data is not safe in the hands of any company with Internet facing servers. I like to think that I know a bit about securing data and networked systems. The truth of the matter is that there will always be someone who could simply walk through any security measures I employ. I don't believe that there is any such thing as a secure system. Even if code and hardware can be made 100% secure, if a person other than oneself has access, it can be compromised.