The yellow oil pan light in the dashboard of my '01 330Ci is slow to extinguish upon starting the car. This occurs even when the oil is topped off. The indicator extinguishes within 30 sec. or so, but I'm wondering if this is normal or a precursor of a failing oil pressure sending unit. I recently changed the oil and filter after about 9500 miles with Castrol 5W-30 SynTec, but the symptom still occurs. Any thoughts?