x-amz-acl Headers not signed

I had an issue where all of my requests were coming back with this:

<Error>
  <Code>
    AccessDenied
  </Code>
  <Message>
    There were headers present in the request which were not signed
  </Message>
  <HeadersNotSigned>
    x-amz-acl
  </HeadersNotSigned>
  <RequestId>
    MyRequestId
  </RequestId>
  <HostId>
    BASE64EncodedHostId=
  </HostId>
</Error>

My presigner uses the official ruby aws SDK:

def presign_foo(name)
    signer = Aws::S3::Presigner.new
    signer.presigned_url(:put_object, bucket: Rails.application.config.s3_root, key: "something_private/#{name}", acl: 'public-read')
end

And it outputs this string: https://foo-dev.s3.amazonaws.com/something_private/my_filename?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=MyCredentials%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20170118T190154Z&X-Amz-Expires=900&X-Amz-SignedHeaders=host&x-amz-acl=public-read&X-Amz-Signature=MySignature

And here is my react component. getSignedPeopleTargeting calls a route that ends up returning the value from presign_foo.

<S3Uploader
    getSignedUrl={this.props.getSignedPeopleTargeting}
/>

Eventually I tracked this down to a line in the s3-uploader that adds the header: https://github.com/odysseyscience/react-s3-uploader/blob/7a26ebc3d0cbfbf3bfb9bec2d0cb28bf147e8b95/s3upload.js#L160

I believe that this header is not needed as I can control the acl in my presign function (tested by making it private). Because all the presigner examples set the acl, can this line be removed? Alternatively, can the if statement be changed to: typeof this.uploadRequestHeaders === 'undefined'?