Crack in the plastic trim does not mean you have a leak or will get a leak. The piece that is cracking is not integral to the seal of the rear window or slider. I have had two cracks on that piece for about 6 months, no leaks whatsoever. When people are posting pictures showing water dripping from the cracks, it is because the leak is in the window seal near the cracks and the water is just flowing down near the cracks. I took my truck to the dealership, had them document the cracks on my records and should my window start leaking in the future ( because of the cracks?) I will have it replaced under warranty. I chose this route because the cracks are nearly invisible and I was more afraid of causing a leak by replacing a perfectly good window. Just my two cents on the issue.