Lots of buffering - is this normal?

[mike]

Should I be worried that it buffers even on smaller requests?

2008/04/21 09:16:33 [warn] 16705#0: *1111856 an upstream response is
buffered to a temporary file /var/lib/nginx/fastcgi/4/00/0000000004
while reading upstream, client: 1.2.70.157, server: domain.com,
request: "GET /foo.php HTTP/1.0", upstream:
"fastcgi://127.0.0.1:11011", host: "domain.com", referrer:
"http://domain.com/foo.php"