Transmission whine

I have a '03 Acura TL with 52,000 miles on the odometer. It has an automatic transmission. Recently I have been hearing a soft whine (barely detectable) I believe comes from the transmission or differential. I hear the whine in the lower gears around town. The transmission operates properly, and does not leak fluid. Is it likely that I’m in for a serious transmission problem?

Does it whine when in neutral if you rev the engine or only while being driven?

Only when being driven. I don’t hear it when I rev the engine and the transmission is in Park or neutral.

Have you checked the fluid level? Your owners manual tells you how.

It is good you are sensitive to your car. Is it still under warranty? If so get it diagnosed by the dealer, for free. There are a number of possibilities but it really needs a diagnosis by in person to isolate the source of the noise, I would not think it a serious problem but it is hard to give any real information at this point.

Yes, I checked the fluid level. It is full and the fluid looks clean.

No, it’s not under warranty.