Not sure about the seals wearing out. BUT-I've heard that leaving the slide out for an extended period of time can (but really? does it?) cause the weight of the slide to kind of start to droop/or sag. That's what I heard. BUT-On a small to medium FunFinder I'm not convinced the weight of the slide will drop. Maybe on a huge fifth wheel where the slide is super heavy with appliances or a sofa and the dining table and chairs. . . So - having heard what I've heard. . . I store mine (indoors) with the slide out. Some may say that with the slide out in extreme cold or torrential downpour, the seal(s) could leak. . . maybe.