The assassin skill tree had a couple pretty major changes. This means that your assassin's skills will almost certainly change. If you are unhappy with the change please email me at raesanos@armageddon.org and we'll work something out. I think most people will be happy with the change, though. The main purpose of the changes was to give characters more reasonable access to some of the guild's more useful skills.
Note: You may not immidiately have all the skills you should have, but they will appear pretty quickly. Again, if you have questions about this, feel free to email.