When I get ready to cut my fabric, I unfold the fabric and look to see how the fabric was cut at the store as the fabric may look straight, but in reality, it is not. Therefore, I open up the fabric and tear the fabric so it is straight. I then measure a little over what I need so I do not have the 'ravel' ends and I do not refold the fabric. Then I cut the width I require for my sewing project. Yes, this takes a little more time, but that is okay. Reason, sometimes, the material near the fold line is not perfectly straight and it could be off just enough so one would not be able to use that portion of the strip (I know as it has happened to me more than once).
Therefore, before you cut, open up your fabric to determine how straight it was actually cut at the fabric store. The unevenness could also be how the manufacturer placed the fabric on the bolt.