The shop that is restoring my 4 speed '70 Challenger said that ECS's carpet is ACC. What my restorer does, is order a ACC carpet early in the week. That way it gets delivered before the end of the week, and has only been rolled up in the box for a couple days and hasn't "set" in the rolled up state. Then upon receiving it, he unrolls it in a place that gets alot of sun, and leaves it there for a week or so before installing it.
End result is the same flat carpet ECS sells for about half the price. I just looked at it briefly when I visited the shop last month, but from what I can see, looked great!
I don't know if he orders directly from ACC or what he does. Certainly if you get it through a reseller, it may have been sitting rolled up in their warehouse for a while before it was shipped to you? Or maybe the carpet is dropped shipped directly from ACC?