An aftershock measuring 3.5 on the Richter scale rolled through the Palm Springs area, but it was hardly noticed by local residents and caused no apparent damage, authorities said. The aftershock was related to the 5.9 earthquake that struck Southern California on Tuesday morning. Meanwhile, an elderly woman admitted to Desert Hospital in Palm Springs with chest pains possibly brought on by the main temblor was reported improved and in fair condition. Two other patients with earthquake-related problems were listed in fair and good condition, respectively. At Eisenhower Medical Center in Rancho Mirage, two patients admitted for chest pains remained in satisfactory condition.