Yeah, I've been hit with "You are being Hunted" 5-6 times now while exploring the plains. Heck, I got hit with it while sailing the ocean (didn't stick around, maybe I should have).

My main base in the meadows has been hit with all the other raids once. I do have small portal bases in the other biomes but I don't think that's the reason. Not complaining, but I wouldn't mind seeing the others pop up more often