Why does Heroku always find unresolved dependencies?

I haven't installed any gems since the last time I deployed, but Heroku keeps thinking there is something new I suppose, and that significantly slows down my deployment time. How can I make sure that I don't get this message?

EDIT:

This is from my deployment message. I dunno...is it normal?

Writing objects: 100% (13/13), 1.88 KiB, done.
Total 13 (delta 10), reused 0 (delta 0)

-----> Heroku receiving push
-----> Rails app detected
-----> Detected Rails is not set to serve static_assets
       Installing rails3_serve_static_assets... done
-----> Gemfile detected,开发者_高级运维 running Bundler version 1.0.7
       Unresolved dependencies detected; Installing...
       Using --without test:development:staging
       Fetching source index for http://rubygems.org/

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$ git add Gemfile.lock
$ git commit -m "We should always check in Gemfile.lock in our applications."
$ git push heroku master

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I contacted support and they resolved it.