  The spin alignment matrix element rho_{00} for the vector mesons K^{*0} and
phi(1020) has been measured in RHIC at central rapidities. These measurements
are consistent with the absence of polarization with respect to the reaction
plane in mid-central Au + Au collisions whereas, when measured with respect to
the production plane in the same reactions and in p + p collisions, a
non-vanishing and p_perp-dependent rho_{00} is found. We show that this
behavior can be understood in a simple model of vector meson production where
the spin of their constituent quarks is oriented during hadronization as the
result of Thomas precession.
