Our 99 is the same way, but seems to plug the fill hole. When I first discovered it, I was worried and the dealer invited me to just buy a new dipstick. I never got around to it, and haven't had a problem 4 years. I give it a good look when I change the oil and it never looks different and doesn't leak.
2015 Ford Fusion Titanium, Ecoboost 2.0L turbo, Magnetic (metallic gray)
2015 Chevrolet Silverado 1500 Double Cab, 4x4, 4.6L V6, Black