"Grey Area"?

I had my beta test this morning and my nurse just called me back with results and said that I'm in a grey area. She said in order for the pregnancy test to be negative it has to be less than "5" but in order for it to be positive, it has to be greater than "25" and my levels are falling between 5 and 25. So I am increasing progesterone and going back for more blood work in two days. Has this ever happened to anyone else? I'm very confused and don't know what to expect.