can you get a faint positive then after the allotted time it disappear?

okay so I took a 88 c pregnancy test and it came back with a visible second line. about 20-30 mins after taking the test to me it looked negative. can that happen? I read that some women had that happen and that they where in fact pregnant just not even hcg for the positive to stick on the test. has this happened to anyone and what are your stories