Good to have them replaced now under warranty - it's also one reason people give them a bad name, because they do wear down. Yours sound like a defect though. I bought my JKU with LSD, even though open wouldn't have bothered me either. I expect they will die before 100k though from wear alone.
2013 JKU Sport, billet, auto, 3.73, LSD, 315/75/16 Duratracs on MB 72, 10A springs, Bushwacker flatties
Sold - 2005 TJ, red, auto, 3.73, 33" Duratracs, 4" lift
Ice storm casualty in 2007 - 2003 TJ, green, auto, 3.73, 33" Duratracs, 4" lift