Genital warts diagnosis

ok i have been with my gf for a year now. before this i have not had sex or anykind of sexual contact with a woman for about four years. my gf gets yearly paps test and std testing. before we had sex for the first time she got tested just like she always does. she was clean. then 6 months later she got tested agian becuase she was leaving the country for a year to teach and wanted to cover all the bases before she left. she was clean and did not have anything. now she has been gone about six months and i just got diganosised with having genital warts? how is this possible? i know they stay dormant for years but could they really have stayed dormant for that long in side of me? thanks for the response.