Interesting enough the ZOC and ZOI (Zone Of Influence) definitions were discussed to some length some time ago. ZOC was deemed to mean the area you have control over that others could not enter without permission or declaring war, which in the entire GC series is at the edge of the tiles your planets are in. ZOI is the extent over which you have influence in a commercial sense. So your ZOI could extend to another player's planets and could, with time, cause the planet to flip their allegiance to you. Being able to see everything within your ZOI is dependent on you having the sensor reach to do so.
Also, what you have shown has been true all the way back through the alpha, and is consistent with what happens in GC1 and 2.
