We have had several propane hoses chewed by squirrels. Only happened at one campground across 2 different years. We had been camping there for 5 years. The difference being, the hoses only got chewed on when they were laying across a flat surface. The two times they got chewed was when the grill and camping stove were on the picnic table and the excess length of hose was laying on the table. When the hoses just hang down and don't lay on the ground or table, they don't get bothered.
I also put Frank's Hot Sauce on the propane lines now to be safe. It's a terrible waste of hot sauce, but it's cheaper than replacing propane hoses
-Michael