you can also slip a second layer of stabilizer under the hoop if you see it start to pucker. I was just at a store and the lady said to always use two layers of stabilizer. I've only been using one and haven't had problems, I only embroider on cotton quilt fabric so far.
I did buy some stabilizer from that lady, and after using it I can see why she'd say to use two layers. I don't think I'll be buying that brand again.