I'm kinda amazed he just blurted it out so quickly. Obviously, his lifespan would be seen as irregular pretty quickly, but he should already know how big a deal a goblin that can get 80 years of skills would be, and maybe come up with a somewhat better lie like "oh I have a lifespan of a year or two", and admit that it was just a defensive lie later on when he lives past that and is already powerful enough to defend himself from a few high-end attackers/assassins.