when I scanned my Ubuntu 10.04 with rkhunter a root kit hunter toolkit, it gave following warning:

Is there something that I have to worry about.

            [23:06:19]   /usr/sbin/adduser                               [ Warning ]
            [23:06:19] Warning: The command '/usr/sbin/adduser' has been replaced by a script: /usr/sbin/adduser: a /usr/bin/perl script text executable
            [23:06:20]   /usr/sbin/rsyslogd                              [ Warning ]
            [23:06:20] Warning: The file properties have changed:
            [23:06:22]   /usr/bin/dpkg                                   [ Warning ]
            [23:06:22] Warning: The file properties have changed:
            [23:06:22]   /usr/bin/dpkg-query                             [ Warning ]
            [23:06:22] Warning: The file properties have changed:
            [23:06:24]   /usr/bin/ldd                                    [ Warning ]
            [23:06:24] Warning: The file properties have changed:
            [23:06:24] Warning: The command '/usr/bin/ldd' has been replaced by a script: /usr/bin/ldd: Bourne-Again shell script text executable
            [23:06:24]   /usr/bin/logger                                 [ Warning ]
            [23:06:24] Warning: The file properties have changed:
            [23:06:25]   /usr/bin/mail                                   [ Warning ]
            [23:06:25] Warning: The file '/usr/bin/mail' exists on the system, but it is not present in the rkhunter.dat file.
            [23:06:27]   /usr/bin/sudo                                   [ Warning ]
            [23:06:27] Warning: The file properties have changed:
            [23:06:29]   /usr/bin/whereis                                [ Warning ]
            [23:06:29] Warning: The file properties have changed:
            [23:06:29]   /usr/bin/lwp-request                            [ Warning ]
            [23:06:29] Warning: The command '/usr/bin/lwp-request' has been replaced by a script: /usr/bin/lwp-request: a /usr/bin/perl -w script text executable
            [23:06:29]   /usr/bin/bsd-mailx                              [ Warning ]
            [23:06:29] Warning: The file '/usr/bin/bsd-mailx' exists on the system, but it is not present in the rkhunter.dat file.
            [23:06:30]   /sbin/fsck                                      [ Warning ]
            [23:06:30] Warning: The file properties have changed:
            [23:06:30]   /sbin/ifdown                                    [ Warning ]
            [23:06:30] Warning: The file properties have changed:
            [23:06:31]   /sbin/ifup                                      [ Warning ]
            [23:06:31] Warning: The file properties have changed:
            [23:06:34]   /bin/dmesg                                      [ Warning ]
            [23:06:34] Warning: The file properties have changed:
            [23:06:35]   /bin/more                                       [ Warning ]
            [23:06:35] Warning: The file properties have changed:
            [23:06:36]   /bin/mount                                      [ Warning ]
            [23:06:36] Warning: The file properties have changed:
            [23:06:37]   /bin/which                                      [ Warning ]
            [23:06:37] Warning: The command '/bin/which' has been replaced by a script: /bin/which: POSIX shell script text executable
            [23:08:58]   Checking /dev for suspicious file types         [ Warning ]
            [23:08:58] Warning: Suspicious file types found in /dev:
            [23:08:58]   Checking for hidden files and directories       [ Warning ]
            [23:08:58] Warning: Hidden directory found: /etc/.java
            [23:08:58] Warning: Hidden directory found: /dev/.udev
            [23:08:58] Warning: Hidden directory found: /dev/.initramfs
            [23:09:01]   Checking version of Exim MTA                    [ Warning ]
            [23:09:01] Warning: Application 'exim', version '4.71', is out of date, and possibly a security risk.
            [23:09:01]   Checking version of GnuPG                       [ Warning ]
            [23:09:01] Warning: Application 'gpg', version '1.4.10', is out of date, and possibly a security risk.
            [23:09:01]   Checking version of OpenSSL                     [ Warning ]
            [23:09:01] Warning: Application 'openssl', version '0.9.8k', is out of date, and possibly a security risk.