Because of that model being in the Salt Series I bet they used some type of Lock-Tite or other compound during assembly. And for a knife that is to be used in a harsh environment I can sort of see why they would do that. But that is the first time I've heard of that.
There are compounds that will help loosen nuts, bolts, screws etc, but do be advised that you might void your warranty in many cases. It's not often that I ever have to take one of my Spyders apart. And I usually won't do it unless it's been in the user rotation for some time.