Since a few people have commented on finding out via HN rather than Dropbox directly (as did I), I thought I'd post that I received an email from them just then

Since a few people have commented on finding out via HN rather than Dropbox directly (as did I), I thought I'd post that I received an email from them just then. In my case though it included "we noticed some potentially suspicious activity during the period", which for me was linking the desktop app. I don't know if everyone will be receiving a note, or just those who fit the potentially-suspicious profile. A quicker notification would have been nice, but I appreciate that they're also obviously looking for any aberrant behaviour.