Wierd name Glitch

Whenever i am alone on my multiplayer server, or a player is very far away (500 blocks atleast) i will sometimes see a name appear, go a bit across the screen, and disappear.
WHAT I WANTED TO HAPPEN
nothing
WHAT REALLY HAPPENED
at least 10 character name run across the screen
HOW IT HAPPENED
1 have no one on, or no one in 500 blocks
2 walk around at night time, in torch light works best
3 watch a name go across the screen (this will not always work)