I have a 2012 2109S and never had a problem with any leakage. I do maintain the seals with the silicone spray to keep them supple and check the top of the slide for debris before closing.
2016 Chevy Silverado 2500HD Duramax LTZ Z71 Extended Cab, Long bed
2012 Dodge Ram 1500 5.7L Hemi (with K&N Air Intake) (traded)
2012 Rockwood 2109S (Sold)
2014 Cougar X-Lite 21RBS