If you search for “lost followers” on twitter search right now you will see loads and loads of people crying about losing followers.
I got 3 emails from people this morning who said my follower count had dropped to 3900. I was like wtf last time I saw it, it was like 2500 ?!?. People are nuts about this Twitter stuff!
Twitter has confirmed there are some issues but its more related to losing people you follow. You can read the official update here
I talked to a developer there this morning via email and he said people should be ready for their follower count NOT to increase because they do not remove the spammers from the count when they ban them. The update yesterday was the first time they had tried removing the spammers from follower counts.
It will be interesting to see how it washes out.