I noticed the same thing with the zip cases that came with my new eXo's. My first impression is not as good as the original zip case, but I will use it and see how I really feel about it. I was very happy with the old zip case before. I always put the ipod inside the eXo inside the zip case when I'm not using it do that it doesn't get dusty.
Well, I don't mind the new zipper. It is a little harder to zip, but that's okay. I think the new material just doesn't feel as sturdy as the old. It kind of feels more floppy almost like a sandwich bag. I liked the old stiffer material. Also, the old zip case barely fit the exo/iPod which meant the fit was very snug which I liked. The new fit is more like throwing the iPod/eXo in a pouch with room to spare. Another thing I noticed is that the new material has a slight grippy texture to it and likes to attract dirt a little more. I am using the new case though right now and it isn't bad; I'll give it a chance for a while.
Thank you for you comments. You will find that the case is very strong and the material is the same as the other TPU so it should react to dirt the same as the other. Over the next few months this information will be collected to make the ultimate zip case. This is one of the reasons it is given away free with each eXo and will be given away free with each Xskn. Have any of you used the zip case to hold and protect something else other than your eXo or for iPod cables.
Actually the new case has grown on me because it is easier to zip up. I know I said it was harder to zip before. What I meant is that the zipper requires more force to zip. The slightly larger size of the new zip case actually makes it easier to zip when in a hurry though.