After further investigation with @danfinlay and team, it appears that the compromise was due to a registrar that has locked up the email domain. 

It appears to have only affected this one account. 

Some more details in thread about what we're doing next.

Latest update

No evidence to believe there is a wider security issue.

Will ship a few additional improvements for boosting the security of individual accounts this week.

Latest update

No evidence to believe there is a wider security issue.

Will ship a few additional improvements for boosting the security of individual accounts this week.

https://warpcast.com/v/0x7a179cea

Thanks for the transparency and the proactive steps to enhance account security. It's reassuring to see continuous improvements even when no major threats are detected. Looking forward to the new features!