We have a 2012 283ts. If you are refering to the outside bottom of the slide-out, on the wall, there is none on ours either. Have been through some heavy rain, both parked and driven through, and never noticed any water intrusion through the bottom of the slides. And, I do check my rig after each rain for any water that may have entered.
However, keep your eye on the seals at the top of the slides. The seals are on a track type mounting, and the seals can sometimes "slide" to the front or more normally to the back, leaving a gap in the upper corner. For awhile I kept finding water on the top of the slide when it was in. Seal had slid back only an inch or so, but it was enough to let a bit of water in.
Used a dab of contact cement to anchor the seal to the seal slide, and also put a small piece of weatherstripping there to supplement the seal.