nginx passenger expires max cached pages

Question

I have posted another question similar to this, which I thought I resolved. But it is coming back with another symptom.

I am using REE/Passenger/Nginx and have the following in my nginx.conf

location ~* ^.+.(jpg|jpeg|gif|png|css|js|swf)?([0-9]+)?$ { expires max; passenger_enabled on; }

Ever since I did this, it seems sometimes, the client gets server with cached pages, like for normal .html.erb pages. So if I go to http://localhost/posts/22 I might see the version of post 22 that was last seen for another user. This isn't happening if I run the app on webrick.