The living room slide out on my 2008 Cardinal 30RKLE appears to be approximately 1"-2" below level on the outboard edge when extended. I'm assuming this is per design to allow rain drainage away from the seals, but am wondering if my assumption is erroneous. Thanks!
I don't have a Cardinal but most if not all slides are designed with a small slope away from the rv for water drainage. IMHO your assumptions are correct.
If your interior trim is flush against the wall (all the way around), everything is ok with your slide. If it is tight at the top and has a gap at the bottom, then you may need an adjustment.