On February 9, 2013 I had a large negative rep event (-100) labeled as "Serial upvoting reversed". I assume this was an automating response to the 11 upvotes my posts received the day before. How does this work? Does it reverse votes automatically if they were cast with too short of a time interval between them? If so, what is that interval? I commonly spend some time quickly skimming new posts and voting on them. I want to make sure I leave enough time between the votes so that they will count.
Basically, if a single user piles you on with lots of upvotes or downvotes, it gers reversed. This helps prevent sockpuppetry, and also stops overenthusiastic new users from voting up every single post of a user who answered their question (happens a lot).
As long as your rapidfire votes aren't all on the same user, you're fine. Try to digest the post before voting, though :)