There is a fairly large gap on mine ('14 28 BHBE), perhaps an inch or more? But I never paid any attention to it. It seals when closed, and seals when open, no leaks, so I'm happy.
Just don't put any weight on it when it's closed, like sitting on the dinette or the couch (Especially along the edge), there is no support under the bottom of the slide in the closed position and you could do damage.
2014 Jay Flight 28 BHBE
2015 RAM 2500 6.4L HEMI, Tradesman 4x4, 3.73
Blue Ox SwayPro (BXW 1503)
Upgraded from an REI internal frame backpack and a Eureka 1/2 dome tent!