3.6 auto whining noise near redline

Hi all,

I have a 2012 3.6 automatic. Today I had to accelerate quickly and noticed a whining belt-like noise near redline. 

Maybe it's normal and always been there but I never noticed since I rarely floor it. I tested it again later....same noise at over 5,000 rpms. 

It crops up around 5,000 rpms and gets louder at the revs increase. Anyone else noticed this sound? Sounds like a serpentine belt to my ears. Can't hear it at all until higher rpms. Thanks.