People lie, I'm sure you've lied to close friends before, or at least not told the whole truth.
If it wasn't a serious topic than your frustrated by the fact that he lied to you and not the lie itself, in which case just remember everyone lies sometimes and they usually have some reasons to do it. Unveiling all truthful information constantly can sometimes be dangerous, just tell him you didn't appreciate him lying and be done with it. There has to be a level of trust not only for him with you but you with him, that if it's an important topic he wouldn't lie to you.