  At temperatures below 1 K, the capacitance of a glass sample changes due to
the application of a DC field in accordance with A. Burins dipole gap theory.
However, we now report that below 20 mK, during the first sweep cycle of the DC
electric field the capacitance is smaller by about $10^{-5}$ compared to any
subsequent sweep. Despite this overall shift the field dependence follows the
dipole gap predictions. In a subsequent sweep to higher DC fields the
dielectric constant drops by about $10^{-5}$ as soon as the applied field is
higher than any field previously applied. A picture involving the dynamics of
resonant pairs provides a qualitative description of this behavior.
