The gaps probably appear due to sub-pixel rendering and your unusual control system. If the hotspot is centered and the object as an odd width/height, this makes the object edges land between pixels, e.g. a 5x5 object with a centered hotspot (at 2.5 x 2.5) placed at (10, 10) has its right edge at X = 12.5. Since Platform only works to the nearest pixel it leaves a half-pixel gap which can appear as a narrow space.
Secondly why do you set the vector manually instead of using the control system? The Platform behavior wasn't designed to be controlled that way and it seems the push-out algorithm leaves a gap. If I set it back to default controls and disable your events it doesn't leave a gap. I'm not sure why it leaves a gap your way, but wouldn't it fix it to just use the behavior's control system?
Still, for the next build I've increased the is-by-wall detection to 2px.