RHR increased from 60 bpm to high 90s 1 week after stopping Zoloft (sertraline). Related? Should I be concerned? Recent ekg showed normal sinus rhythm. Causes?

Not sure. If this persists another week it is highly unlikely to be from zoloft (sertraline) withdrawal. Other things that can cause an increase in your RHR can be a pulmonary embolism. If you traveled recently by car or plane or have other symptoms such as shortness of breath or chest pain you should go to the ER.