What's going on? In fact, it's not unusual for the sun's northern and southern hemispheres to be out of synch. As long ago as the 19th century, solar cycle pioneers Spoerer (1889) and Maunder (1890) noted that there were often long periods of time when most sunspots were found preferentially in one hemisphere and not the other. This plot from the Royal Observatory of Belgium shows assymetries throughout the last 6 solar cycles:
One possible explanation for this phenomenon may be that the two hemispheres of the sun have their own solar cycles, one out of phase with the other by about a year. Indeed, Solar Max is often double peaked. You can see it in the hemispheric sunspot plot. In the three most recent cycles (22-24), north peaked before south, creating two surges of solar activity separated by a "Gnevyshev gap." Solar Cycle 25 might continue this trend.
A complete discussion of sunspot asymmetries is included in David Hathaway's excellent review article "The Solar Cycle."