Security checks are a part of our firewall that we implemented due to a denial of service attack we suffered in June 2019. They will likely remain for the foreseeable future, as they protect the forums and servers from attack. Unfortunately, the filter used to detect a legitimate user from a bot is not perfect, and so sometimes a human will be asked to go through the check or what-not. It's nothing you've done, it's just the algorithm they use that will never be 100 percent perfect.
Sorry.