My /User directory permissions always changes… should I be worried?
Install iTunes 11.2.1

Source: http://support.apple.com/kb/HT6251

Description: Upon each reboot, the permissions for the /Users and /Users/Shared directories would be set to world-writable, allowing modification of these directories. This issue was addressed with improved permission handling. For information on the general content of iTunes 11.2.1, see http://support.apple.com/kb/TS5434.