Gap/Banana/Old Navy have always been inconsistent. I think that part of it is that they machine die cut (which many high volume vendors do). When the die is pressed into the fabric, the upper layers stretch. The sewers still use a 1/4 to 5/8 seam allowance. But the variance in the fabric cut causes significant size differences within the same size. Some vendors machine cut, but use a computer assisted saw type blade, that seems to provide a more consistent size.