2006 Toyota Corolla with only 30k miles, automatic tranny. I am the second owner and the records show it was maintained properlyand according to schedule. The automatic transmission shifts smoothly, however it makes a rather anoying whining noise, only at certain speeds and loads, and is more pronounced after the car has warmed up. Transmission fluid level is OK and the fluid color is dark red. Did I buy a lemon? Is this anything to worry about? Or is this a known issue with these models, maybe another sign of slipping Toyota quality? Anything I can try besides replacing the tranny fluid?