Gavan,
Check out this chart:
http://www.mba.com/the-gmat/gmat-scores ... means.aspx Those are your raw scores, which are translated to percentiles. You actually did equally well in both math and verbal.
Based on this chart your percentiles were about 80 for both math and verbal.
My guess is that the math questions you missed were rated a little more highly than were the verbal problems you missed. Missing a highly rated problem does not hurt your score as much, because the GMAT does not expect many people to get them right. There may have been a slight effect too on where in the test you missed the questions; there is a slightly larger adjustment of your score earlier in the test.
Anyway, you are doing very well--congratulations!!!