Unfortunately, yes it's normal. Our above floor lippert slide, and some of the schwinteks we've had did have visible daylight underneath, with or without the bottom wiper. Doesn't look the best, but solved this with a pool noodle while set up camping. Mainly to keep the cold air, mosquitos and anything else out.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.