My slide cover over the larger slide does the same thing. I was told the sag won't hurt anything as the weight just pulls extra awning out of the roll. Just retract the slide, it will dump the water. Or if you have a step stool you can reach up and pull down on the handle, it will wind in the extra awning. Every time I do that it dumps off the opposite side of the slide so I stay dry. I have heard of the air wedge, however if it doesn't hurt anything why pay the money and risk damage if you forget to pull it out!
Phil, Michelle, Logan and Wyatt
2006 Dodge 2500 Heavy Duty 5.7 Hemi
2012 Rockwood 8312ss