That was one of the hallmarks of the titanium foil shutter; it could really take a whacking before it being broken to the point of being totally unusable, so a few small creases or 'wrinkles' is not any cause for alarm, a deeper crease could cause a tiny light leak but that would look Obviously Damaged. The Nikon F seems particularly vulnerable due to its one piece removable back.
I recall when the F3/MD-4 combo was released the sales rep would come to the camera shop where I was a young buck and open the back of the F3, set a slow shutter speed, stick his thumb thru the film gate while the shutter was open; then run the shutter/motor at continuous with the shutter bouncing off his thumb, then pull out his thumb and keep motoring to demo the toughness of the shutter and motor combo (the jamming F2 MD-2/3 was a topic of conversation in this shop).