Here in the NE, damp Crawls are common. What most folks do is cover them w/6 mil plastic and 'weigh' the edges down with gravel or bricks, or whatever. This prevents moisture from evaporating up, and into the house itself. The vents can even promote evaporation.
As for what's 'normal' in Texas, I don't know. Visit your favorite Home Center or Hardware store and ask around. Talk to your neighbors if they have crawls too. Because of the heavy rains, EVERYONE may be having this problem, hence, 'no problem' (assuming the problem is only as you describe.)