I haven't checked my June Tailor things -
but in thinking about how I cut my strips with a ruler - they are almost always a smidgen larger than what I'm supposedly measuring.
Example: I put the desired ruler line on the edge of the fabric - then cut - there is a tiny space between the edge of the ruler and the rotary blade. It might only be 1/64 of an inch or so - but it does eventually make a difference.