As already suggested, it could be a scam.
Have you had an email, telling you to change your password by "clicking on the following link"??
If so, delete the email and ignore it, as it'll prob just take you to a fake site where you'll input your details for the scammers to obtain.
If in doubt, access your gmail account via a trusted method, such as using your favourites, or by typing the address into the address bar.