Yes, if the tab is stuck in the threads there will be some damage. But you have to look at the totality of the situation. There are a lot of clean threads left around the vast majority of the steerer. Also when the threaded cup is removed and reinstalled it will, to a degree, clean up the small spot of damage. So go ahead and pull off that washer trying to be careful but knowing that a small amount of thread crushing is not a problem that will cause any real issue. Andy.