If I contracted vCJD 20 years ago, wouldn't I be symptomatic by now?

As a former service member stationed in Germany between 1988 and 1991, I am ineligible to donate blood. However, supposing I happened to contract vCJD, the human variate of Mad Cow Disease while stationed there: wouldn't I now be symptomatic? If I've not been back to the country since, what, precisely, are they worried about? And why the disparity for length of stay for service members versus resident Europeans during this time period? Are service members somehow more susceptible to vCJD? Do they think we're all potential carriers? what gives?