One can plot the deviations of MICA's Earth positions from the best fitting Keplerian ellipse positions. The result is rather curious. The motion appears to be that of compounded spirals. The smaller cycles are due to the Moon's motion.
The blue dot at the end point marks the last data point.
Supplemental (Apr 6): A 0.0002 AU distance deviation along the ecliptic path of the Sun is enough to account for the observed 16 min deviation in the time of the Spring Equinox.