my ABS actuator started to leak ironicly 3 days after the Master brake cylinder was replaced. What you want to check for is any fluid around the rear bottom of the passenger seat check the carpet and pull off the little door and look for any signs of fluid down there. Fill it back up and have someone press the brake pedal and check the actuator for any leakage.
Kai 14.765 @ 92.22m.p.h. #4 in 2002 on Z32racing.com in NA drags (206.4 RWHP)