The oil light on my 97 Avalon (1MZ-FE) stays on for about 3 secs after I start the car, then goes out. It started doing this recently, like in the last 2 or 3 months. Engine has 150,000 miles on it. Is this normal? I don't believe that there is much sludge in the engine, but the valve covers havent been off in at least 60k miles