I wonder how high the chance is of the master password itself having been reused, and of one of _those_ password sets getting compromised. Although I'd expect most people using a password manager would not be likely to reuse a master password.

On the other hand, my paranoia is now kicking in and I am on my way to change my (non-LastPass) master password, just in case past-me was very stupid a few years ago and then forgot about it...