I think the wording of the translation of the recall in Japan carries more weight than any potential mis-servicing of the brake fluid. I quote, “… the brake operating simulator, assembly oil used during manufacturing may seep into the pressure sensor due to an inappropriate manufacturing process. Therefore, during use, the resistance part within the sensor may corrode, causing the output value to become abnormal, causing the warning light to illuminate, the failsafe to activate and the force required to operate the brake pedal to be increased.”