why does empty file /media/.hal-mtab-lock have suid bit set?

[Les]

HI, Dave,
	This is a "lock" file, used to prevent multiple access to another file.
When the other file is opened by an application, that application
generates the lock file to signal that the file is in use.  When the
application closes, the lock file is deleted and the next application in
the thread que for access can open and write to the file.  It is to
prevent write errors on your disk.

Regards,
Les H
On Tue, 2007-11-20 at 08:47 -1000, Dave Burns wrote:
> I stumbled upon the follwoing:
> 
> #rpm -qf /media/.hal-mtab-lock
> file /media/.hal-mtab-lock is not owned by any package
> 
> #ls -la /media/.hal-mtab-lock
> -rwS-----x 1 root root 0 Jun 25 12:44 /media/.hal-mtab-lock
> 
> # file /media/.hal-mtab-lock
> /media/.hal-mtab-lock: setuid empty
> 
> I find this strange. By googling I get the impression it is a valid
> hald file, but why the weird permissions?
> 
> Thanks,
> Dave
>