If you aren't doing anything illegal then don't bother trying to hide your IP from every server on the internet. It's still a good idea to use reasonable care, but generally a good hardware and software firewall combination will keep your computers safe. Having someone actually know your IP doesn't significantly increase the risk.
Samutz probably has logs that include the IP used to upload each file. I would expect these records are necessary for the security and maintenance of the service. These records most likely go unread month after month and eventually get recycled to the bit can, unless there's a problem.
A not entirely hypothetical example: A hacker infiltrates the chain game, deliberately corrupts the save, gets his IP banned from GTAForums, and creates a new account by drawing a different IP through a proxy server to continue causing trouble. Samutz can ban the entire subnet for the proxy server and speed up the process of weeding out the bad apples.
Are you a bad apple?
Added: You should be more concerned about how Google, Microsoft, and other big brother companies are tracking your preferences, location, etc. based on your IPs. We know they actively track and use this information in an effort to get more money out of you, and who knows what else.
Edited by OrionSR, 21 April 2013 - 08:06 PM.