upstream timed out

[Reddirt]

I am a newbie.

I'm running Ubuntu, Nginx and 5 Thin servers - that serve up a Ruby on Rails
app.

The system hangs about once a day.

The Nginx log has this error:
2013/07/11 10:06:46 [error] 21344#0: *201 upstream timed out (110:
Connection timed out) while reading response header from upstream, client:
192.168.10.11, server: ,

and 

2013/07/11 10:05:11 [warn] 21345#0: *225 an upstream response is buffered to
a temporary file /opt/bitnami/nginx/tmp/proxy/2/00/0000000002 while reading
upstream, client: 192.168.10.11, server: , request: "GET
/assets/application-b7b1695e978934a03ade49d20bf63139.js HTTP/1.1",
upstream:

Is this telling me there is a problem with Thin or Ruby on Rails?
I'm not seeing error in logs for those systems.

Thanks,
Reddirt

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,240762,240762#msg-240762