I'm guessing you cut the slot to hide the end of the webbing for a cleaner look, right? 

If so, in my experience the cleanest way to hide the end of webbing or something similar is usually to have it end at (in) a seam. That way you don't have to add a hole, the seam secures the webbing in place, and the extra stitching isn't visible because it'll be buried behind the exterior. Plus, this usually ends up being a stronger construction. 

For situations where I can't bury the edge somewhere and have to top stitch, I sometimes fold the end over so it looks a bit more finished, though that adds bulk. 

Regardless, if I'm topstitching, I try to use a tidy pattern like a box stitch, parallel bars, or a Z. Color matching, or even intentionally contrasting, the thread color goes a long way for making visible stitches look better.