wordpress upload theme timeouts

[Noturns]

When i upload a particular wordpress theme (zip file of 5MB) through Wordpress itself.
This results into an error...

504 Gateway Time-out
nginx


PHP version 5.3
--------------------
error_log shows no errors there (is a new subscription)
php upload variables is set to default
max_execution_time is set to default
memory_limit is set is set tot default
post_max_size is set to 8M
upload_max_filesize is set to 8M
file_uploads is set tot default

I have created a new wordpress application in order to reproduce this error.
I have enabled error_reporting = E_ALL

The problem did not appear after that, however it might be because i only removed the theme from FTP.

Any suggestions?