You might want to change the email for your bitcointalk account.
This is the only thing I have not done however I don't think it's relevant. I changed my email password even my hosting accounts password and also 2FA before it happened.
When you changed your password and logged in again, you might have forgotten to click the Always logged in button.
I can't remember but I actually don't make mistakes on this kind of stuffs. Checking the stay logged in button is kind of pre-setup thing in my mind. I never miss them.
I don't really think theymos is working on a server, maybe its an hacking attempt on your account. Only theymos can address the real issue behind, until you don't have much to do other than changing your email.
This is the only way for me to confirm that actually something happened which was cause by the system or on my side, however I am curious to know if anyone else had this issue ever.