If you ever get to the Mountain Man museum at Cody, Wyoming, take a look at the Jim Bridger rifle. They bought that from me.
What I recall about the rifle is that there isn't nearly as much wood in the forearm as with modern rifles, and a heckuva lot more steel in the barrel. With respect to this discussion, I imagine that moisture's effects were less than one would encounter in today's wood-stocked rifles. And, odds are that the stock was coated with either some sort of wax or with animal fat.
In today's world, with short-term exposure to bad weather, a waxed stock will most likely suffer little change in bedding pressures. Three or four days shouldn't be a problem. Were I concerned, I'd shoot a test group at the end of the hunt, double-checking for any change in point of impact.
One test is better than a gazillion Internet squabbles.