I received a mail by checksecurity from my ubuntu 12.04 server with the following content:

--- setuid.today    2012-06-03 06:48:09.892436281 +0200
+++ /var/log/setuid/setuid.new.tmp  2012-06-17 06:47:51.376597730 +0200
@@ -30,2 +30,2 @@
-  131904  4755   2 root       root           71280 Wed May 16 07:23:08.0000000000 2012 ./usr/bin/sudo
-  131904  4755   2 root       root           71280 Wed May 16 07:23:08.0000000000 2012 ./usr/bin/sudoedit
+  143967  4755   2 root       root           71288 Fri Jun  1 05:53:44.0000000000 2012 ./usr/bin/sudo
+  143967  4755   2 root       root           71288 Fri Jun  1 05:53:44.0000000000 2012 ./usr/bin/sudoedit
@@ -42 +42 @@
-  130507   666   1 root       root               0 Sat Jun  2 18:04:57.0752979385 2012 ./var/spool/postfix/dev/urandom
+  130507   666   1 root       root               0 Mon Jun 11 08:47:16.0919802556 2012 ./var/spool/postfix/dev/urandom

First i was worried, then i realized that the change was actually 2 weeks ago, i think there was a sudo-update back then.

Since checksecurity runs in /etc/cron.daily i wondered why i only get that email now. I looked into /var/log/setuid/ and found the following files:

total 32
-rw-r----- 1 root adm   816 Jun 17 06:47 setuid.changes
-rw-r----- 1 root adm   228 Jun  3 06:48 setuid.changes.1.gz
-rw-r----- 1 root adm   328 May 27 06:47 setuid.changes.2.gz
-rw-r----- 1 root root 1248 May 20 06:47 setuid.changes.3.gz
-rw-r----- 1 root adm  4473 Jun 17 06:47 setuid.today
-rw-r----- 1 root adm  4473 Jun  3 06:48 setuid.yesterday

The obvious thing that confuses me is that the file setuid.yesterday is not from yesterday = Jun/16.

Is this a bug?