Will a crack in the exhaust manifold cause you to fail smog?

I live in california. I just failed the visual portion of the smog check although the car passed all emission tests. Is this correct? Is my mechanic trying to rip me off? The crack obviusly doesnt go all the way through as there is no exhaust leak.
Will a crack in the exhaust manifold cause you to fail smog?
It is bad on the valves. can allow exhaust into the cabin as well. the laws in CA are pretty tight, and not that I know the applicable law, but it seems reasonable.