I identify a source of \Lambda_{QCD}/m_Q corrections to the assumption of
quark-hadron duality in the application of heavy quark methods to inclusive
heavy quark decays. These corrections could substantially affect the accuracy
of such methods in practical applications and in particular compromise their
utility for the extraction of the Cabibbo-Kobayashi-Maskawa matrix element
V_{cb}.Comment: 16 pages, 5 figures, an abbreviated version of hep-ph/9809279, the
original JLAB-THY-98-03 ``Duality in Inclusive Semileptonic Heavy Quark
Decay