Why do I have to precompile my assets in development?

Question

Lately I have to precompile my assets to see my css changes in my development environment. I don't know why this, the environment setting config.assets.debug is still set to true. I find this rather annoying, I believe I didn't have to run precompile after every change before. How do I make rails compile on page load again?

I'm running Rails 3.1.3. I don't know what other info to provide, please let me know what you need to know to solve this.