I attempted to log onto the Terraria server and I got shown a message saying "Mana Hack - create new character". I will admit I do have an inv editor and I have used it, but i didn't use it on this character. I only have one hacked character and hes only for flying about on single player and blowing up a worlds. But I never used the editor on this character before.

EDIT:
I just remebered that I did click on darks name by accident once on the inv edit, his mana was at 138 out of 140 so I hit the regen button.