How many times have you met a fighter and he told you that he was a World Champ or undefeated? Probably a lot. But, guess what? Most of the time they are exagerrating or lying. Nobody should ever try to impress you with what they have done. Unfortunately this is prevalent in martial arts. So, don't be fooled by people when you here these things. If you go to train with somebody, ask around or google them (there will be a video or some paper trail) to validate what they say. If you find that they are lying, let them know it.