Another explanation might be an increase in Twitter spam. I can only speak for myself, but I've been getting tons a spammy followers over the past couple weeks.

Another explanation might be an increase in Twitter spam. I can only speak for myself, but I've been getting tons a spammy followers over the past couple weeks. You'd think that the most popular accounts (like the ones highlighted in the article) would see the highest levels of spam, thus the sharp increase in new followers. I'm sure the suggested followers feature Ev mentioned plays a part as well.