Is the slug size normal?

I just started using Rails 3 on Heroku and was surprised at how much bigger the slug size (28MB) is compared to using Rails 2.3.5 on Heroku (less than 5MB). Is this normal? It's a simple application that only uses the reque, aasm, and unicorn gems. Everything else is the default.

source 'http://rubygems.org'
gem 'rails', '3.1.0.rc4开发者_开发百科'
gem 'pg'
# Asset template engines
gem 'sass-rails', "~> 3.1.0.rc"
gem 'coffee-script'
gem 'uglifier'
gem 'jquery-rails'

gem 'aasm'
gem 'resque'

# Use unicorn as the web server
gem 'unicorn'

group :production do
  gem 'therubyracer-heroku', '0.8.1.pre3'
end

-----> Heroku receiving push
-----> Ruby/Rails app detected
-----> Installing dependencies using Bundler version 1.1.pre.5
       Running: bundle install --without development:test --path vendor/bundle --deployment
       Using rake (0.9.2)
       Using aasm (2.2.0)
       Using multi_json (1.0.3)
       Using activesupport (3.1.0.rc4)
       Using bcrypt-ruby (2.1.4)
       Using builder (3.0.0)
       Using i18n (0.6.0)
       Using activemodel (3.1.0.rc4)
       Using erubis (2.7.0)
       Using rack (1.3.0)
       Using rack-cache (1.0.2)
       Using rack-mount (0.8.1)
       Using rack-test (0.6.0)
       Using hike (1.1.0)
       Using tilt (1.3.2)
       Using sprockets (2.0.0.beta.10)
       Using tzinfo (0.3.29)
       Using actionpack (3.1.0.rc4)
       Using mime-types (1.16)
       Using polyglot (0.3.1)
       Using treetop (1.4.9)
       Using mail (2.3.0)
       Using actionmailer (3.1.0.rc4)
       Using arel (2.1.3)
       Using activerecord (3.1.0.rc4)
       Using activeresource (3.1.0.rc4)
       Using coffee-script-source (1.1.1)
       Using execjs (1.2.0)
       Using coffee-script (2.2.0)
       Using rack-ssl (1.3.2)
       Using rdoc (3.8)
       Using thor (0.14.6)
       Using railties (3.1.0.rc4)
       Using jquery-rails (1.0.12)
       Using json (1.5.3)
       Using kgio (2.5.0)
       Using pg (0.11.0)
       Using bundler (1.1.pre.5)
       Using rails (3.1.0.rc4)
       Using raindrops (0.7.0)
       Using redis (2.2.1)
       Using redis-namespace (1.0.3)
       Using sinatra (1.2.6)
       Using vegas (0.1.8)
       Using resque (1.17.1)
       Using sass (3.1.4)
       Using sass-rails (3.1.0.rc.4)
       Using therubyracer-heroku (0.8.1.pre3)
       Using uglifier (1.0.0)
       Using unicorn (4.0.1)
       Your bundle is complete! It was installed into ./vendor/bundle
       Cleaning up the bundler cache.
-----> Creating ERB based database.yml
-----> Rails plugin injection
       Injecting rails_log_stdout
       Injecting rails3_serve_static_assets
-----> Preparing app for Rails asset pipeline
-----> Discovering process types
       Procfile declares types      -> web, worker
       Default types for Ruby/Rails -> console, rake
-----> Compiled slug size is 28.3MB
-----> Launching... done, v59

yes, it's perfectly fine. Especially since it's Rails 3.1 since it has dependency on a few large gems like rubyracer etc.