Well thats possible. But Nginx -V gives me correct version and shows that SPDY module is enabled and configured ...

When I do which nginx on terminal it returns /usr/local/sbin/nginx

Can you tell me how can I check which binary is being used for the app?

$ nginx -V

nginx version: nginx/1.3.13
built by gcc 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)
TLS SNI support enabled
configure arguments: --sbin-path=/usr/local/sbin/nginx --prefix=/etc/nginx --conf- path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-client-body-temp-path=/var/lib/nginx/body --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-log-path=/var/log/nginx/access.log --http-proxy-temp-path=/var/lib/nginx/proxy --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --lock-path=/var/lock/nginx.lock --pid-path=/var/run/nginx.pid --with-debug --with-http_addition_module --with-http_dav_module --with-http_gzip_static_module --with-http_realip_module --with-http_stub_status_module --with-http_ssl_module --with-http_sub_module --with-http_xslt_module --with-http_spdy_module --with-ipv6 --with-sha1=/usr/include/openssl --with-md5=/usr/include/openssl --with-mail --with-mail_ssl_module --add-module=/software/ngx_cache_purge-1.6 --with-openssl=/software/openssl-1.0.1e