User blog comment:The wiki bunny/Robin's bounty increased to B.100,000,000/@comment-3119203-20120212030534/@comment-4778877-20120212035208

I see what you're getting at. But if you think about it, you see the rest of the strawhat's bounties except Robin's after the timeskip. and she was with the revolutionaries during the timeskip. so maybe she fought with them and her bounty increased. it's just what I think.