2004 x5 4.4i, 79,500km.

I have recently noticed a noise with my transmission, it sounds like a "hoot" or whistle, or maybe something rubbing. I can reproduce every time:
- Drive for about 10-15 minutes to warm up
- Go to a steady speed of between 60km/h and 80km/h
- Quickly press the accelerator to downshift
- You will hear the "hoot" noise as the transmission downshifts (4 to 3, I think)

There is a link below to a recording of the noise. Sorry for the poor quality, but you get the idea.
http://www.pmttech.com/postings/x5_Shift_Noise.mp3

I took it to the dealer to get check out, and the SA said that there is a software update coming out in September that will fix the issue, and said something about "binding gears"(?). To me, it sounds like BS that a software update would fix this noise, but I suppose anything is possible.

Can anyone here give me a second opinion? Does anyone else have this noise?

(I only have a few hundred kms on the warranty, and I am worried that the transmission will fail just after it expires )