I have had a 7 character password since I opened the account when they first opened up to any old (American) writer. I have the dashboard set as a favorite, so I wasn't mis-keying the address.
Today, I went to check something and it told me I had to change my password. Password now has to be 8-15 characters and include at least one capital (eta - capital letter, not geographic capital) and one number.
I figure they made some change and now anyone who doesn't already meet the criteria is being forced to change the password. So no need to panic. At least I hope not. If anyone says it's not happening to them and their password doesn't meet the criteria, then I might panic :D