SDO is in an inclined orbit, so it's geosynchronous rather than geostationary. As a result the eclipse season it experiences does not necessarily coincide with the eclipse season experienced by geostationary satellites. For geostationary satellites eclipse season is pretty much the same from year to year for a given location.

Think of it like this, the orbit of sdo travels north and south of the equator by up to about 29 degrees. That means the sun earth and spacecraft can be lined up at times of the year that are distant from the equinox. Because the orbit gradually changes over time and the timing of when it crosses the ascending node of the orbit changes over time, so the eclipse season itself will change over time from year to year. This doesn't apply to geostationary satellites whose orbits are always at 0 degrees inclination and effectively have no ascending node (the point in the orbit where it crosses the equator heading north).