  We derive an explicit expression for the leading term in the late-time,
large-distance asymptotic expansion of a transverse dynamical two-point
function of the XX chain in the spacelike regime. This expression is valid for
all non-zero finite temperatures and for all magnetic fields below the
saturation threshold. It is obtained here by means of a straightforward
term-by-term analysis of a thermal form factor series, derived in previous
work, and demonstrates the usefulness of the latter.
