Today someone downvoted my answers serially:
The hostile downvoting activity took place within a short span of time. How should I act?
The downvotes should be revoked within 24 hours by an automated process; if you still see them after 24 hours, post a comment here so I can ask a dev to look into it.
Beyond that, there's generally not much action needed on your part. If it does happen again in the future, you can always post on meta or flag one of your posts so we can look into it, but we only issue warnings/suspensions in cases of particularly egregious behavior, since even the calmest of people can get angry at times and not think straight.