On the CNN webpage, they break down the Webb-Allen race Exit Results by age and gender.

With some simple algebra, one can compute the exit totals at 47.9% for Allen and 51.1% for Webb from the gender splits and 48.2% to 51.0% from the age splits.

Remember that the mid-afternoon exit poll had Webb ahead of Allen by 5%.

Also, remember that the exit poll results are updated by later exit polls and actual precinct results when these become available. If the Virginia exit polls moved from a 5% Democratic advantage to a 3% advantage in just a few hours, that suggests that the later exit polling might be turning toward the Republicans.