isChildOf() function?

thanks to your help my new flash app is running pretty well
i can still make it bug out for a few seconds if i try tho and i would like your help again to improve it
i have several objects on the stage and a MOUSE_OVER on any of these will add a menu popup child and tween it from off the stage
a MOUSE_OUT will tween the menu away and remove the menu with removeChild
heres the bug:
if i mouse out and then quickly mouse over the same object while the menu is tweening away before it has been removed, it doesn’t add the menu again, and then on the next mouse out, it tries to remove the child menu, which isn’t currently a child because it was just removed, and i get the error:
TypeError: Error #2007: Parameter child must be non-null.
at flash.display::DisplayObjectContainer/removeChild()
at menucaller/tweenOffTimerEnd()
at flash.utils::Timer/_timerDispatch()
at flash.utils::Timer/tick()
is there a way i can use an if statement to make sure that the menu is a child of the parent before removing it? i think this will fix the problem if it is possible to do so