My question would be, "how do slide toppers cause this to happen?" If you are talking about the weight of them, it is on opposite corners of the 'box' and should pick up on the front near the floor. If you are talking about the spring holding them in, the springs are not strong enough to cause that. To me, that doesn't add up. I haven't had mine open but a couple of times since Christmas but haven't noticed anything. Will take a look that is for sure!
2012 Sandpiper 365SAQ weighing @ 15k, Onan, 2nd air, slide toppers, TST
2013 F350 6.7L Lariat 4x4 CC DRW,Viair 1007, Ride-Rites, Edge CTS, B&W
2001 Chevy 3500CC DRW 4x4, 8.1L, 4.10 gears w/ Detroit TrueTrac
2001 Ford Excursion Limited 4x4 7.3L,V/B Spring Mod, ProComps, Hellwig Swaybar, & other 'Necessities'