Since it seemed to start after the fluids were changed, make sure the bolts on the tranny fill and drain holes are properly tightened to oem torque specs. The crush washers will leak if not crushed enough. I would say the same on the motor oil pan bolt but that looks dry in the pics. Quite often something leaking at the rear of the valvecover area will end up at the tranny below, have a peak around the rear valvecover with a bright flashlight. Make sure the valvecover is tightened down to spec if it was opened in recent times.