  X-ray reverberation lags have recently been discovered in both active
galactic nuclei (AGN) and black hole X-ray binaries. A recent study of the
neutron star low-mass X-ray binary 4U 1608-52 has also shown significant lags,
whose properties hint at a reverberation origin. Here, we adapt general
relativistic ray tracing impulse response functions used to model X-ray
reverberation in AGN for neutron star low-mass X-ray binaries. Assuming
relativistic reflection forms the broad iron line and associated reflection
continuum, we use reflection fits to the energy spectrum along with the impulse
response functions to calculate the expected lags as a function of energy over
the range of observed kHz QPO frequencies in 4U 1608-52. We find that the lag
energy spectrum is expected to increase with increasing energy above 8 keV,
while the observed lags in 4U 1608-52 show the opposite behavior. This
demonstrates that the lags in the lower kHz QPO of 4U 1608-52 are not solely
due to reverberation. We do note, however, that the models appear to be more
consistent with the much flatter lag energy spectrum observed in the upper kHz
QPO of several neutron star low-mass X-ray binaries, suggesting that lower and
upper kHz QPOs may have different origins.
