I would suggest you add some room to the Y at which enemy can still see the player, though... Like this:
abs(Player.Y - Enemy.Y) < 20
So when the player gets within 20 pixels of Enemy's Y position, it gets frisky. You can adjust that for height of enemy sprites too, if you want, such as:
abs(Player.Y - Enemy.Y) < Enemy.Height
Depends where you have hotspots, you can adjust at will.