Bill,
If you were entering or even
CROSSING through a NATIONAL PARK SERVICE property, including NPS roadways, you probably would have been arrested, or at least had your weapon confiscated.
I ran into this when I cowboyed in Co. in the 90's. The company I worked for had numerous commercial outlets all throughout the Rockies...to get from 1 to the other we had to drive through or on NPS controlled "scenic routes". They had very large and clearly posted signs stating "NO WEAPONS ALLOWED ON NPS PROPERTY".
Very few people are aware that the NPS is a FEDERAL LAW ENFORCEMENT AGENCY with all the same, if not more, police powers as any other police dpt. in the country. They can issue citations, make arrests, confiscate "contraband" items, etc.
They even have thier own version of a S.W.A.T. team, that is also trained in High mtn. operations. Those guys are every bit as deadly and fierce as any Force Recon Marine, Green Beret, Navy Seal, etc. In fact that's where alot of those guys go after leaving the service.
All I can say is that you got lucky on that one...