Are there supposed to be cases where the enemy sees you, but you never see them?

Either the models on the screen, or icons on the minimap? I just had a case where an enemy that was chasing me saw the edge of my model and thus on the minimap, however when I look at the replay from my vision perspective, they are NEVER shown; either the model or the icon. Isn't this a bit off? If someone sees you shouldn't you see them? Or did they add a realism factor in this silly way by being able to see farther in the way you are facing (your champions 'eyes' lol...).

Cost me a death [zombie-nunu-tears]

BTW, this was at the choke on the other side of the wall from blue side blue buff, where you go up to the river crab/baron, I was going down and around the blue wall to my blue area and they followed through the same choke.