Hi, I had a clean remote database I was running mongorestore.exe against, and the process mirrored that of a successful one even though I completely forgot username and password. Database size was under 64MB, and no rows were restore of course but three specific collections (though empty) kept comming through. It took some time before I discovered this, it might help others if they get a warning.
System:
mongodump.exe from 2.0.4 remote
mongorestore.exe on 2.0.4 remote
Ran from 2.0.4 windows locally

Standard dump restore with deletion of the system.index (I even got an error during restore when index was included, but no docs came over anyway).