no such file to load -- json (first request only)

As the title suggests, I'm getting that error ONLY on the first request to the application. Subsequent requests work fine. This is occurring on several of the ma开发者_StackOverflowchines I'm running the application on.

I'm not using anything JSON related in this app (at least not that I'm aware of).

I should also point out that adding gem 'json' to the Gemfile makes the error "go away". I'd be ok with this, but I'm afraid there's something more sinister at work here that will turn into a code-bomb later.

This is Rails 3.0.3 and Ruby 1.8.7.

Some of your files may require json. Try to install json with:

 sudo gem install json

Or

Add gem 'json' to Gemfile and do bundle install