Nginx catching all domains without wildcard

[Xavier Cardil Coll]

My Nginx config is catching all subdomains without specifying a wildcard. I
have created an special config for each subdomain, but seems that all
subdomains pass trough the main domain configuration. I have discovered
this by removing the subdomains configuration files from nginx.conf and
watching how it still catches all the subdomains, so when I send a request
to uk.domain.com, instead of Nginx catching the subdomain configuration,
goes through the main domain configuration. This is causing trouble with
applying mod_pagespeed individually to each of the sites and also managing
the GA universal code.
The config for the main domain is this :

http://pastebin.com/4AvGgRCc

http config :

http://pastebin.com/CkJLHyHH

If I haven't setup a wildcard, how come the main domain config is catching
all subdomains ??

Thanks
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