499 in a proxy environment and short execution php scripts

[Alex Findale]

Hello Nginx

Before writing this I have checked the meaning of the 499 error code as 
result of that the client closed the connection before the server 
answered the request. Thats clear as water.


PROBLEM: Iam measuring the execution time of the requests, and I see 
that in general for all sites clients are generating 499 errors with 
different php scripts whose execution is under 1 second.

QUESTIONS:
a.) I would totally understand this behaviour in scripts that take more 
than a few seconds but why would i see so many 499s for quick scripts?

b.) Would it be possible that my proxy setup would be causing premature 
499 as explained? I have :

client_body_timeout 10;
client_header_timeout 10;
keepalive_timeout 15;
send_timeout 10;
proxy_connect_timeout 15;
proxy_send_timeout 60;
proxy_read_timeout 60;

Regards,

Alex F