I typed "sudo nautilus" - what to do now?

I typed in "sudo nautilus" because I didn't know that I should never do that O.O

But now it's to late. What can I do now?

I just typed that in to see if it throws an error. (Yes, I'm a Ubuntu newbie)

I've read that I should type find $HOME -not -user $USER -exec ls -lad {} \; and find -not \( -user ${USER} -group ${USER} \) in the console to see if files are corrupt, but it does not show me anything in the terminal.

Can someone help me?

The command sudo nautilus will open the file browser with extra (superuser) permissions, for instance you could move or delete important system files. However, if you didn't do that, then there's no harm done. Once the window is closed, that's it. Next time you open nautilus it will be with your own normal permissions.