  Inflationary predictions based on the linear theory of cosmological
perturbations are related to the two point function of a (second quantized)
real scalar free field during the accelerated stage. Such a two point function
is finite, in contrast with its coincidence limit, which is divergent due to
the ultraviolet divergences proper of field theory. We therefore argue that
predictions of most of the inflationary models do not necessarily need a
regularization scheme to leading order, i.e. tree level, which is required
instead for non-linear corrections or calculations involving the
energy-momentum tensor. We also discuss unpleasant features of the "would be"
regularized spectrum obtained using the traditional fourth order adiabatic
subtraction.
