I have the warn sliders on my TJ. Mine doesn’t have that bowing issue but I do have an area on my passenger rear area where the slider has a fair gap from the body. My driver side was perfect. Not sure if I rushed the passenger side install and drilled the holes slightly off but I haven’t gotten back to try and correct it. It does collect dirt and grime in that gap. I will say I rinse that gap out the best I can. I did fluid film the body prior to tightening down the bolts. I also caulked the seam between the slider and body. Every spring I do loosen the body bolts and separate the slider from the body enough to get a good rinse and reapplication of fluid film as well as to ensure no rust is brewing underneath. I will say I do like these sliders. Here are pics of that spot.
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https://www.4wd.com/sku/Warn/standard/71500.pdfLooking at the instructions, seems as if you elected to not drill the sugguested mounting hole that might have resolved this issue.
The Warn suggested hole is actually drilled above the “W” in each rock slider. Which leads me to believe me that this issue would be non existent under light to mediocre offroading.