whining/whirring under the hood
 

I've got 2013 es 350 with 10,000 miles on now. I have recently noticed that there was whirring/whining noise coming from the engine(I guess) while accelerating up to 45 mph. It seems that the noise goes along with the RPM since it gets louder when accelerating and it goes away when decelerating. I am wondering if this is normal that people experience on 2013+ es 350. A friend of mine drove the car once before but did not hear anything until I told him about the noise, so I guess it is not very noticeable to some people. At the 10,000 miles check up at the dealer, I mentioned about it and they said they did not hear anything, but I know for sure there is whirring/whining noise.

Does anyone have this and know why?