preg test questions

Hello fellow IM's i have a quick question regarding pregnancy tests!
i really hope im not jinxing myself but here goes.....
Hubby and i have for the last 9 months been trying for baby #3, so far with no luck :( bit of back ground we fell very easily with our first two - we only had to look at each other and i was pregnant haha, anyway less than a week ago i did a home preg test, it showed a negative so i through into our small toilet bin, today i was cleaning our bathroom and emptied bathroom bin into other bin to take outside only to pull the tester out and have another look and there is a second very VERY faint line, barely visible but its there {just} i thought i was imagining things but popped my glasses on and could see it faintly....... with my first the preg test was also extremely faint and hardly visible {that was at about 7-8 weeks} with baby number 2 preg test was negative at 7-8 weeks but when going to dr and doing his test he said there's a faint line but its there. so i know home preg tests for me are hard to gauge so heres my question
since i left the preg test for just shy of a week before seeing the line could it have come up {even if i was not preg} simply becasue it had been sitting for a while...... or does the amount of time passed not make much difference..... im not sure if i should take any notice of this test due to the fact it has been sitting for under a week. my period is late but for me thats not uncommon for me.
i am going to wait it out til the end of the week and if nothing by Monday i will go to dr for blood test, until then i'm going to stare at this bloody test all day for the rest of the week wondering if its just wishful thinking......
anyone know much about these tests..... i know im clutching at straws but if it is possible for the second line to show after a while of sitting {without being preg} than at least i can not get my hopes up.
TIA