So I was getting ready to make myself a new core world, and started browsing through my leader pool looking for a suitable governor. As I was browsing, I noticed the diplomat I had assigned to the Torians sitting there in my leader pool. I wondered how the heck he got there, and went to the diplomats screen to put him back with the Torians. There I discovered that apparently the Torians had declared war on me. I was totally unaware that they had declared war on me. I went back a reloaded a save from a few turns before, and the Torians had apparently declared war on me at least before that save.
So I had played a least a few turns with the Torians at war with me, and I never even knew I was at war. With all the annoying pop up windows that block everything until you interact with them to get them out of the way, you would think of all things somebody declaring war on you would be one of those pop up windows. It should be in great big letters in a pop up that fills the whole screen like "THE TORIANS HAVE DECLARED WAR ON US !!!!!"
But nope, I had no clue at all I was at war with the Torians until I was just casually browsing through my leader pool, and just happened to notice the diplomat to them has been unassigned.
Please make it much much MUCH more obvious when another civ declares war on the player.
Happy Bug Squashing!