Paperclip routing error in Rails 3.1: only applies to new images - ruby-on-rails-3.1

Question

I am having essentially the same problem as this questioner: Paperclip routing error. The server gives a 404 for a static file (which is present!), so Rails gets called and then there is a routing error.
My Rails 3.1 app uses paperclip to attach files, but when serving files in production the following error is logged by Rails:
Started GET "/system/images/9/thumb/Large%20image.jpg?1320149338" for [...]
ActionController::RoutingError (No route matches [GET] "/system/images/9/thumb/Large%20image.jpg"):
Corresponding to an NGINX access log entry:
"GET /system/images/9/thumb/Large%20image.jpg HTTP/1.1" 404 728 "-" [...]
So, a few observations:
This didn't happen in the past, and past images with almost identical URLs still work, e.g.: /system/images/1/thumb/StoneSkimming%20Demyhb%20Art%203.jpg is served correctly.
The image files were uploaded, and converted by ImageMagick, correctly - I have verified all the expected files are in the right place, and are valid JPEGs with the right image in them.
Permissions for the files are all as expected, and match the files that still work.
The entries in the database for the relevant model look correct.
Adding/removing the query string, or putting the URL directly into the browser gives the same result as the embedded <img> tag: the image is not found.
Can anyone point me in the right direction here? I am having trouble working out how to test/debug this because the error is not universal across the app.
I am using Capistrano to deploy, so /public/system is a symlink to the shared directory. My instinct is that this is not the problem though, as older images in the same location work just fine.

Answer 1

I managed to solve problems with paperclip when deploying with capistrano to production by adding to capistrano deploy config:
namespace :deploy do
desc "build missing paperclip styles"
task :build_missing_paperclip_styles, :roles => :app do
run "cd #{current_path}; RAILS_ENV=production bundle exec rake paperclip:refresh:missing_styles"
end
end
after("deploy:update_code", "deploy:build_missing_paperclip_styles")
Probably there is better solution.