Salt is not significantly hygroscopic. It doesn’t draw water to itself (it does a little bit, but not much.) The reason salt draws water out of meat and vegetables is related to the osmotic balance between the inside and outside of the cells. Even then, it’s not actually drawing the water out, it’s just creating a state where it’s statistically probable that water will be on the outside of the cell wall. This creates an effective force on the water when you take a very large number of molecules into account. But flour does not have cells.

Just don’t put fresh bread in a sealed plastic bag. Bretzel or no. You’ll be fine. Notice even grocery stores put their bread in paper or perforated plastic. I usually leave home-made bread out uncovered the first night.