Could it have something to do with your browser settings? I only have to do that once I have cleaned every possible history from my browser or run CCleaner.
I have my browser forget history on exit, and i run CCleaner every now and then. I really don't want to change it to remember history. Sadly, this is the only site/forum that does this for me.
But for the sake of experimenting, i will change the setting now and report back.
EDIT - ok, so after some testing, here's what I found. You are indeed correct, Firefox will make me confirm my age when I have it set to forget history. When I changed it to remember, after logging in, and confirming my age, I closed it, and the next time I logged in, it went straight into the Witcher forum. Though after changing it again, it was back to confirming my age.
I also have Internet Explorer, and it too is set to forget on exit. After changing it to remember, it was the same as Firefox. I then decided to go back to forgetting history on exit, and played around with the advanced cookie settings, and got it prompt me on every single one, and added those to 'always allow'.
When I reopened this time, the forum page knew who I was. I got the window with your name, instead of confirming I'm not a robot. I signed in, clicked on the Witcher page, and it went right in. I logged out and changed back the cookie settings to accept, and closed IE.
Opened it again, bought up the forum home page. Again it bought up the window with my user name, and I was able to sign in and go to the Witcher page without confirming my age.
We'll see what happens next time, lol.
EDIT - well today, IE is asking me for my age again. So I have no idea anymore what's going on. I haven't touched anything since yesterday when all was fine.