I think what masterplum means is that he was playing in a game that did NOT have a dedicated jungler. And so there was probably a champion who was solo who would duck into the jungle, pick up some minions and make it back to lane without wasting XP.
And doing this he managed to out level everyone?
And if this is the case then it's not something you have to worry too much about. In actual competitive play both teams should have someone who is full time jungler. This means the jungle isn't just going to be sitting around available for other people on their team to take for bonus XP.
--
~Ç~ Eff_Dee
http://img.imgcake.com/FDjpgyb.jpg