Flutter Hero animation does not use theme colors?

When creating a simple Hero animation with an icon in the appbar in a MaterialApp, the hero animation does not seem to use the theme color unless the color is explicitly specified in the icon itself. Can someone explain why the color of the icon is changing during flight when the icon color is not explicitly set? Does the Hero not have access to the Theme data? Or does it use another color set?

Example:

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: Hero(
          tag: "mytag",
          child: Material(
            color: Colors.transparent,
            child: IconButton(
              icon: Icon(
                Icons.menu,
                // uncomment below line and the flying icon is white as expected...
                // color: Theme.of(context).primaryIconTheme.color
              ),
              onPressed: () {
                Navigator.of(context).push(
                  PageRouteBuilder(
                    pageBuilder: 
                      (context, animation, secondaryAnimation) => SecondPage()
                  )
                );
              },
            ),
          ),
        ),
      ),
    );
  }
}

class SecondPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        actions: <Widget> [
          Hero(
            tag: "mytag",
            child: Material(
              color: Colors.transparent,
                child: IconButton(
                icon: Icon(
                  Icons.menu,
                  // uncomment below line and the reverse flying icon is white as expected...
                  // color: Theme.of(context).primaryIconTheme.color
                ),
                onPressed: () {
                  Navigator.of(context).pop();
                },
              ),
            ),
          ),
        ]
      ),
    );
  }
}