Hi Naomi,
Not every person using discover gets the 'disappearig line" thing. You will know by ow if it is. I got a positive and went back and there was no line.
It doesn't sound like that is what happened with yu. I have heard people rave about Discover and have only good things to say. There is a whole speel on the nternet somewhere about these tests and there disappearing positives. However if yours still hs that line then I would take it as a positive. Test again this morning. Please letme know!