  We explore the analytical properties of the traceless stress tensor 2-point
function at zero momentum and small frequency (relevant for shear viscosity and
hydrodynamic response) in hot, weakly coupled lambda phi^4 theory. We show
that, rather than one or a small number of poles, the correlator has a cut
along the negative imaginary frequency axis. We briefly discuss this result's
relevance for constructing 2'nd order hydrodynamic models of hot relativistic
field theories.
