Is this positive?

I haven't experienced exactly that, but spotting can mean different things at different times, so it's really best to do a proper test or see your PD to know for sure rather than guess lah. Since you're already 4 days late, a home test should be pretty reliable now if you haven't tried one yet. A few of us have had confusing spotting situations before and it always helped to just get checked out so we could stop wondering and know what's going on.