Paperclip, S3, Heroku: Missing Image

Long time viewer, first time asker. I've searched for this topic but don't believe I've found the answer.

I have a Post model that has an image. I'm using the Paperclip gem, saving to Amazon S3, and hosting on Heroku.

The file upload form works fine, because I can see that images are sent to my S3 bucket.

The issue is that, the images don't actually show in production.

Here's my model:

class Post < ActiveRecord::Base
    attr_accessor :image_file_name, :image_content_type, :image_file_size, :image_updated_at
    belongs_to :user
    has_many :reviews

    has_attached_file :image, styles: { medium: "700x500#", small: "350x250>" }
    validates_attachment_content_type :image, content_type: /\Aimage\/.*\Z/

And here's my config/production.rb:

# Required for Paperclip / AWS
config.paperclip_defaults = {
:storage => :s3,
:s3_credentials => {
    :bucket => ENV['S3_BUCKET_NAME'],
    :access_key_id => ENV['AWS_ACCESS_KEY_ID'],
    :secret_access_key => ENV['AWS_SECRET_ACCESS_KEY']
    }
}

And here's my show.html.haml file:

.clearfix
    .post_image_description
        = image_tag @post.image.url(:medium)
        .description= simple_format(@post.address)
        .description= simple_format(@post.description)

Shouldn't the @post.image.url be enough? What may I be missing to properly route to the image?

This is what I see when I pull Heroku Logs:

2015-06-23T15:38:26.181383+00:00 app[web.1]: ActionController::RoutingError (No route matches [GET] "/images/medium/missing.png"):

For reference, here's my repository for the project: http://ift.tt/1K9XOih

Please let me know if there is anything else to provide in the question, too. As this is my first time asking. Thanks everyone.