Pregnancy

I went to the hospital the other day and I had a pregnancy test and blood work done so I can make sure that I'm not pregnant. The result came back <0.5 which means that there's a possibility but it would be less than a week that I'm pregnant if I do happen to be. I have to wait two weeks or so before going to the doctors again and taking another test. Should I be worried or should I take this with a grain of salt?