Enable two factor authentication. In future if someone will be able to get your password again, the two factor authentication won't let him to logon. The google's two factor authentication sends an OTP (one time password) on your mobile via SMS. To enable two factor authentication follow these steps:
1. Click on your email at right upper corner of your Gmail inbox
2. Select Account = account settings page will appear
3. Click on Settings on the list on your left side
4. Enable "2-step verification"
I am an Information Security Professional, you can contact me any time for free help. I am available at: security.koenig-solutions.com and www.rahulkokcha.com