sometimes, yes. when metal is heated it expands.
you have to understand the operating temps these cast, restrictive manifolds run at, in the thousands of degrees on most turbo cars, so failure is quite common as the cars get older. volvo, mitsu, my car, srt, evo, sti, SR20det... all of them eventually will crack and go bye bye. hell my mani is already cracked, but not yet all the way through.