False positive with a tesco pregnancy test?

[bunny1110000to]

took two pregnancy tests yesterday, one in afternoon and one in morning (tesco). they were both negative within the development time. I was emptying my bin and the morning one has now turned into a positive line (obviousy after the development time), but the pm is still showing negative. does this mean im pregnant or is it common for tests to turn positive after a while

[Guest]

probably an evaporation line. you can't get a false positive and as one had a line but other didn't and that it was past development time would say it's probably an evap.