They sure sound like bots. That's not the only thing I've seen though.
Sometimes I'll see somebody comment on a post and immediately they receive something like 12 likes. Then they comment again and get 12 likes from the same users. They have like-bots following them around.
How in the world did I get bots posting on it?
I have no idea. It's weird that a bunch of them just swarmed onto your post. That's the kind of thing I would expect to see on a high-valued trending post. But this just seems so random.