Is it Client or Server who dissapears players after a teleport?

As well people knows in this forums, we all use teleport plugins, kind of Essentials and stuff like this, well I found a Bug but I'm not sure if is Bukkit or Minecraft Client bug.

When someone teleports to you (by example tphere command on Essentials) you cannot see them until they move like 5 blocks (radius), but as they loaded everything back when they teleported, they can see you normally.

I would like to know if this is a Minecraft Client issue, or is because Bukkit server doesn't send to all players the signal that a player have just appeared there.

If this is Bukkit bug please lets repport it on Leaky (Is that the tickets place right? xD)

 

Moved to appropriate forum.

 

Oh, Sorry, I'm bad at some english words

 

Bump? I really wanna read a solution or at least to see if I should post this error on Leaky...