Gemfileを修正したらbundle install

しないと、以下の様なErrorが出て、herokuにpushできない。

git push heroku master
Counting objects: 91, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (81/81), done.
Writing objects: 100% (91/91), 30.37 KiB, done.
Total 91 (delta 5), reused 0 (delta 0)
-----> Ruby/Rails app detected
-----> Installing dependencies using Bundler version 1.3.0.pre.2
       Running: bundle install --without development:test --path vendor/bundle --binstubs bin/ --deployment
       You are trying to install in deployment mode after changing
       your Gemfile. Run `bundle install` elsewhere and add the
       updated Gemfile.lock to version control.
       You have added to the Gemfile:
       * sqlite3
       * thin
       * pg
 !
 !     Failed to install gems via Bundler.
 !
 !     Heroku push rejected, failed to compile Ruby/rails app

To git@heroku.com:xxxxxxxxxxxxxxxxxxx.git
 ! [remote rejected] master -> master (pre-receive hook declined)