I've just realized; the last time I actually SAW one was several days ago, so it might be some undocumented anomaly. My transformers have been dying a lot recently too, so maybe there is something in my save i need to vaporize.
Hmm. I noticed it starting to happen when the cyborg boars came out to play for the first time. Though, if that were the case, I feel like they'd just destroy Kerfur flatout.
Now that you mention it, this happened around the time when the boars spawned... My best guess is they are somehow a part of it. they DO target Kerfur units when they see them.
They do, but usually that ends up destroying them. At least... I think. Unless for some reasons, boars in particular turns Kerfur off instead of destroying him.
