Update

My friend pulled up in a 2010 G37 with the 7AT, he popped it into Manual mode and he had the exact same sound. He popped it into Drive and it went away. 100% the same thing that is happening in my 5AT.

So I am going to say now that this is normal, from what I saw today.

I had previously gone to the dealer and got my ATF tested, When I went to the dealer the sound was not happening so they could do nothing, and the ATF test came out clean.

Link to ATF UOA

 

Very interesting. I'd check mine, but any weird sounds would more likely be due to the cold weather :/