I believe Brain is right. If you look back I mark the sp as a system object by running

sp_MS_marksystemobject

against it.

It is not a documented procedure but what it does is change the bitmask of the status of the object to match with system type. Problem is once done there is no real safe way to undo (can be done don't get me wrong) and as long as marked as a system type you cannot drop thru EM (sorry didn't try thru QA and wasn't really worried since is a test server I got to rebuild in the next few months anyway). Once you do that and restart the server, your results should match up.