Strange: my old database still runs even though I changed the CP password

I recently changed my Control Panel password to make it stronger. I was able to log in using the new password. I thought this would break my connection string to my database, which uses the old password, but it did not. I started and stopped my website and "recycled" the database, but much to my surprise, the old database refuses to die. Any ideas of why it still works? It's been two days now since I changed the password and the database with old password is still running.

Not an urgent question but I'm curious why this happened.