being hacked via ssh with X11 forwarding?

[<debuser@platinum.globalmart.com>]

>From my Linux box at work, I was using ssh to connect to my personal ISP.
I had X11 forwarding turned on.  When I went to log out I got this
message: 

Waiting for forwarded connections to terminate...
The following connections are open:
  X11 connection from shell.schwa.net port 1087

Is someone from that machine hacking me?  If so, how would he do this? If
not, what does it mean?  I see there is a user logged onto my ISP from
that machine.  What logs should I be looking at for information?

Thanks,

Gerry