Water Seeps into my Dometic Awning during Storage

I noticed that my newer camper did that also. My older camper did not. Both had the same length awning, only difference was the old camper had a center support arm. I noticed over time, the newer camper awning tube was sagging in the middle during storage. With the middle sagging, water would accumulate there. I added the center support to the new camper, and when storing, I cinch up the center just a little higher than the ends. Water no longer accumulates.