Those Schwintec slides have separate motors for each side and although linked they stop when they meet resistance. They tend to cut off at slightly different times based on resistance of each side.
As long as the bulb seal, seals completely there should be nothing to worry about. If that gap gets bigger, then you might want to have it looked at.
The old "above floor slides" were ram driven (in the bottom middle), so the bottom was tight, the top, not as much but you rarely saw it.
PLEASE do not send questions via Private Message, my inbox fills up too quickly. Post questions in the forum as a new thread so that other users can benefit from the answers. Use Private Messages for sensitive information only (VIN, Contact info or things you do not want the public to see).