Certificate not trusted on Chrome

Does anyony knows why this happens? I have to open bitbucket.org on Firefox or Safari then go back do Chrome to make it work.

Something in my network?

"The site's security certificate is not trusted!
You attempted to reach bitbucket.org, but the server presented a certificate issued by an entity that is not trusted by your computer's operating system. This may mean that the server has generated its own security credentials, which Google Chrome cannot rely on for identity information, or an attacker may be trying to intercept your communications.
You cannot proceed because the website operator has requested heightened security for this domain."

Opening in Firefox or Safari also makes a security dialog appears, but it lets me accept the exception and go forward.

Thanks!