'application.css isn't precompiled' ... but it is

Hi,

I'm getting the following error when I try to load a page when I have
config.assets.precompile set to false:

Sprockets::Helpers::RailsHelper::AssetPaths::AssetNotPrecompiledError:
application.css isn't precompiled

In my config/environments/production.rb, I have:

config.assets.manifest = Rails.root.join("public/assets")

And I have verified that public/assets/application.css and
application.css.gz are both in fact there with the correct contents.
And also verified that they are readable by the server.

But I'm still getting the error: ActionView::Template::Error
(application.css isn't precompiled)

I'm running ruby 1.9.2, rails 3.1.3 in production mode, and passenger
3.0.11.

Thoughts?

Thanks.

Enabling digests fixed this for me.