When I run vlock or vlock -a on the console as a normal user, then type in
password, FC4 vlock complains:
$ vlock -a
The entire console display is now completely locked.
You will not be able to switch to another virtual console.
Please enter the password to unlock.
Error sending status request (Operation not permitted)
No error messages were printed by vlock in FC3.
This warning is silenced in audit-libs >= 0.9.3.
The audit(-libs) should be probably updated in fc4 too.