Recently there were many public disclosure's occurred where hackers are publishing user data on
public portals, you may have fallen victim.
There is innovative web app out in Web which scans Web to check if your email id is compromised?
When you visit site http://shouldichangepassword.com , you have to provide email id you want
to check and click Check It.
Though this looks like phishing scam, This is site is authentic and worth giving try.