"Unexpected Machine Code" warning from iTunes Connect

After I uploaded my build to iTunes Connect by using Application Loader, I got an email about an issue "Unexpected Machine Code" see below.

Unexpected Machine Code - Your upload contains both bitcode and native machine code. When you provide bitcode, it's not necessary to include machine code as well. To reduce the size of your upload, use Xcode 7.3 or later, or any other toolchain that removes machine code.

I am so confused about this warning. Is this a new thing in iTunes Connect? Why it doesn't give me the warning when I upload QA build but Release build?

Update: I upload QA build last week, it wasn't any warning. And today (June 27th 2016) I upload Release build, it send me the warning.

Just got this as well, it's a bug. I uploaded the near exact same binary as I did a couple of days ago which went through fine (only change was to the version and build number). Developer support confirmed this.

If you do get the e-mail, don't worry about it. Your binary will still process and you'll still be able to submit it to the app store.

Update: both of my binaries which received this message passed review and have been released to the app store.