It should, but you may knit tight, or changing the stitch pattern may affect it; the 3x3 is more like ribbing and that would draw it in. How many sts per inch are you getting? Measure that, then divide it into the 138 sts and that should be close to the full size. It may be a bit longer when you get some more length to it which will stretch out the stitches to a longer length.
sue- knitting heretic