The problem is the Minecraft UUID System was not considered for NoPremium people and you know that Minecraft Servers must run in Offline mode for working with BungeeCord. When a Premium person logs in with an offline server or a BungeeCord IP, because the server is on Offline Mode the server doesn't interpretate the UUID and thinks that's the player name or something like that (24.05.2014 16:51:54: User fab3a7e6-ce0b-317a-b39c-b73eff556e59 not found!!!). Hope this is fixed early because it could affect all BungeeCord Networks.

ADVICE: This is a minecraft server problem with Offline Mode, not with BungeeCord. This also happened when I put someone on the Whitelist or in the OPs list.