response.headers without "x-runtime"?

rails:1.2.6

curl -I http://localhost:4000/
HTTP/1.1 200 OK
Connection: close
Set-Cookie: _co56_web_session_id=cd290031eadc2ac55593098aee726985;
path=/
Status: 200 OK
X-Runtime: 10
Cache-Control: no-cache
Server: Mongrel 1.1.4
Content-Type: text/html; charset=utf-8
Content-Length: 18292