I just glanced at my profile a moment ago and noticed a significant stream of 20 downvotes on answers all within the same 1 minute.
Could these be automatic, or simply a malicious user with a grudge?
They'll probably be malicious, however, don't worry about them. There are automatic processes that spot this sort of thing and reverse serial up votes and serial down votes.
If the votes are still there tomorrow morning (UTC) then let us know and we'll take it up with the development team.