I just upgraded to Notepad++ v6.5.2 and noticed after installation "- Notepad++ [Administrator]" in the title bar.
The Notepad++ installer is running as an elevated process so that it can make changes to Program-Files and related areas. When the installer then starts or restarts Notepad++ at the end of installation it's running Notepad++ as an elevated process.
Unfortunately, the fix is not easy. For example, see http://blogs.msdn.com/b/oldnewthing/archive/2013/11/18/10468726.aspx and also read the comments on that page.