  On September 26, 2022, NASA's DART spacecraft impacted Dimorphos, the
secondary asteroid in the (65803) Didymos system, so that the efficiency with
which a satellite could divert an asteroid could be measured from the change in
the system's period. We present new data from the Thacher Observatory and
measure a change in period, $\Delta P = -34.2 \pm 0.1$ min, which deviates from
previous measurements by $3.5\,\sigma$. This suggests that the system period
may have decreased by $\sim 1$ minute in the 20 to 30 days between previous
measurements and our measurements. We find that no mechanism previously
presented for this system can account for this large of a period change, and
drag from impact ejecta is an unlikely explanation. Further observations of the
(65803) Didymos system are needed to both confirm our result and to further
understand this system post impact.
