'who' lists a non-existent user

[ntripon]

  On a GNU/linux under Red Hat 9, with coreutils-4.5.3-19, 'who' lists
a user who is no longer logged in :

$ who
nt       :0           Mar 20 19:43         
nt       pts/0        Mar 27 14:55         
nt       pts/1        Mar 26 11:36         
nt       pts/2        Mar 26 11:36         
root     pts/2        Mar 20 19:50 (localhost)
nt       pts/3        Mar 27 20:39

$ last
nt       pts/3                         Sat Mar 27 20:39   still logged in   
nt       pts/0                         Sat Mar 27 14:55   still logged in   
nt       pts/2                         Fri Mar 26 11:36   still logged in   
nt       pts/1                         Fri Mar 26 11:36   still logged in   
root     pts/1        localhost        Fri Mar 26 11:21 - 11:23  (00:02)    
nt       pts/4                         Sat Mar 20 19:58 - 11:19 (5+15:21)   
nt       pts/3                         Sat Mar 20 19:56 - 11:19 (5+15:23)   
root     pts/2        localhost        Sat Mar 20 19:50 - 23:24  (03:34)
nt       pts/2                         Sat Mar 20 19:23 - 19:50  (00:26)


The 'root' session was started by user 'nt' on pts/2 with ssh ; it ended
Mar 20 at 23:24 ; yet, it is still listed by 'who' days after, even though
pts/2 has been reaffected.
  I am sending this report to the addres found in the man page for 'who' ;
if it is not the appropriate address, please let me know.
  Thank you. -Nicolas Tripon