Is the only thing that could make a waistband go a bit wavy in spots is that maybe I didn’t get the grain as straight as I thought? I was making jeans. It’s not too bad because it straightens out a lot when I button the jeans, but still it’s not the best.The problem is more pronounced in the front, which leads me to suspect off grain. As a precaution is good practice to interface the waistband on denim? I tore apart some levis once and they were not interfaced in the band. But I wonder if it could help prevent a wave if I missed the grain a little. And what is the easiest way to see the grain on denim? I did my best, but it was obviously still off.