I noticed the same thing. My upvotes shot to between 43 and 48 within a couple minutes and then stopped.
At first I thought I had posted a hot topic, but then I knew why.
My post is here: https://steemit.com/steemit/@cryptommy/steemit-com-and-an-affiliate-program-could-it-work-pros-and-cons-of-the-system
I thought my post was pretty good so I knew I'd get some votes. But then all that came swarming was the damn bot and gave me pointless upvotes.