Update Implementation AIGridGUI class

src/main/java/BattleShip/AIGridGUI.java

@@ -489,7 +489,9 @@ public class AIGridGUI extends JPanel {
         }
 
         public void mouseExited(MouseEvent e) {
-
+            //Unhighlight cells when mouse exited.
+            BSButton cell = (BSButton) e.getSource();
+            highlightCells(cell, 2);
         }
         public void mouseClicked(MouseEvent e) {}
         public void mousePressed(MouseEvent e) {}