Permission violations

[Anon <regtothismail@gmail.com>]

Hello,

I'm not quite sure whom I should send this report to but recently I've 
noticed that I can remove files which owner is root and that have access 
mode set as 644 (see example below). I'm using Debian wheezy/sid with 
3.0.0-2-amd64 #1 SMP kernel.

# touch rootfile
# ls -l rootfile
-rw-r--r-- 1 root root 0 Nov  8 22:21 rootfile
ouid@laptop:~$ id
uid=1000(ouid) gid=1000(ouid) 
groups=1000(ouid),24(cdrom),25(floppy),29(audio),30(dip),44(video),46(plugdev),105(netdev)
$ rm rootfile
rm: remove write-protected regular empty file `rootfile'? y

And then the file was removed, as you can see I've checked my uid, I've 
also checked whether there is sticky bit in bash or rm:

$ ls -l /bin/rm
-rwxr-xr-x 1 root root 60472 Oct  1 18:48 /bin/rm
$ ls -l /bin/bash
-rwxr-xr-x 1 root root 926536 Apr 10  2010 /bin/bash

Finally I've checked my /etc/sudoers and there is no NOPASSWD set for 
the user.
I've tried to reproduce it with another user but everything works as it 
should, i.e. I couldn't remove files which owner is root, so I assume 
that maybe there was a problem with amd64 testing netinstall iso which I 
installed my system from.

Thanks in advance.