How did I manage to login without Google account?

I have a really strange problem concerning the login to App Inventor. I hadn't used App Inventor for quite a while and wanted to look at and old app about two weeks ago. I am quite sure that I didn't login with my Google account.
I got to a page where I could ask for a new code since I had forgotten my password. I still have the e-mail in my inbox which geave me a code to reset my password and my Firefox browser has saved the new password I created then. It is linked to https://login.appinventor.mit.edu. I found all my old projects, could open them etc..
Now everytime I try to login I'm transferred to the Google account login. I can login, but of course none of my old projects are there. Can anybody tell me what's happening here? I would really appreciate if someone could point out what I am doing wrong here. Im pretty confused and desperate!!!