I haven't noticed any extreme cases, but occasionally I do get messages
appearing when ships are far away or possibly culled.  Usually it seems that it
was because they were  just in the midst of issuing the dialogue.  And as you
say the messages may be triggering after they leave the contact list, but before
they are culled.

The point you raised is good too.  We certainly might want players to evesdrop.
So this issue may be resolved.  I will mark it done-cbb.

Is this still an issue?

The dialog from "traffic" kinds of ships will get displayed until the ships are
actually culled from the game (not just vanished from the contact list). That
typically takes a few extra seconds after when a player leaves a station
(culling should not happen too quickly). 

It would be possible to set a convention that if the player is more than culling
distance away, the messages will not be sent. However, I don't like that idea
because it might be important in the future for the player to hear a distant
message. For instance, a guard may be responding to a distress call. A player
pirate will want to know.

easy to replicate.  Load a new game and then proceed directly to Hoel Lpoint. 
Once in several trips a lingering message will appear.

Can you provide steps to recreate? (just to get in the habit of attaching 
steps to reproduce to the bug report.) Then we can discuss how to handle this 
case, which is actually not a trivial issue.

Station messages and conversations continue to scroll across the top of the
screen even after the player has flown millions of klicks away and all relevant
parties in the conversation have been culled from the Contact list.