AF is late so I thought I would test - I doubt I am pg but it is possible. (and would be bad timing so ...)

Anyway, I used the digital tests for the first time and got a "not pregnant" result as expected, however when I ejected the cartridge there was a faint second line. (it was straight away so not an evap and light blue)

Is this normal for these tests? or does it just mean there is some HCG, but not enough to make the digital test say "pregnant"?