Hummingbird isn't minifying the following files listed in Google Page Speed.
If you check Google Page Speed, you'll notice two theme files are still shown under "Eliminate Render Blocking issue"
Re-checking, and clearing the cache doesn't seem to help. The files aren't listed in the Hummingbirds Minification settings page, ie under Hummingbird > Minification
Is this theme/plugin specific issue?