  In the current era of high-precision CMB experiments, the imprint of
gravitational lensing on the CMB temperature is exploited as a source of
valuable information. Especially the reconstruction of the lensing potential
power spectrum is of great interest. The reconstruction from the optimal
quadratic estimator of the lensing potential, though, is biased. As long as the
intrinsic CMB fluctuations are Gaussian this bias is well understood and
controlled. In the presence of non-Gaussian primordial curvature perturbations,
however, the CMB also acquires a non-Gaussian structure mimicking the lensing
signal. Concentrating on primordial non-Gaussianity of local type, we address
the resulting bias by extracting the lensing potential power spectrum from
large samples of simulated lensed CMB temperature maps comprising different
values of f_NL. We find that the bias is considerably larger than previous
analytical calculations suggested. For current values of f_NL and a sensitivity
like that of the Planck mission, however, the bias is completely negligible on
all but the largest angular scales.
