Why does the LastPass Heartbleed Checker show a site as insecure while other sites show it as being secure?
While there are numerous sites that can test whether or not a website's current certificates are secure in light of the Heartbleed bug, the LastPass Heartbleed Checker investigates more than current security.
The LastPass Heartbleed Checker looks at a website's OpenSSL vulnerability over the past two years while the Heartbleed bug was active. This is why some sites may indicate that a certain website is secure from the Heartbleed bug now, while the LastPass security check may still indicate you need to change your password for that site because of its past vulnerability.
You can use the Heartbleed Checker here.