The shearing process only introduces localized stress (<1-2"), so that won't warp an entire sheet. Unfortunately, this doesn't disprove a manufacturing issue... since yours came directly from the factory, there is no appreciable shelf-time to allow warping to happen, which may take weeks/months. If you can afford it, leave one of the new sheets sitting on the shelf for a couple of months and see if it warps... still not definitive, but one more data point.