I did a clear blue hpt with FMU today. The control line was so faint it was barely visible which led me to believe it was invalid. I left the test without seeing out the full ten minutes (silly i know!!) and it had a clear - sign, but an hour later i noticed the control line is ever so slightly clearer and there is a blue + sign in the test window. has anybody been in a similar situation or know if tests can turn + over time??