Positive, but very very very faint line

So I feel very silly posting this because I have a 9 yr old son so you would think I would know, but I never took a urine test when I found out I was pregnant. I took a blood test. Anyways, I have been feeling very off lately and I'm supposed to start this week. I took a test and I saw a line appear. It is very very very faint. I held it to the light and it's faint, but there. I can't even get a pic because of how light it is. Has this ever happened to anyone and they were pregnant? Or could it just be my eyes playing tricks? I'm not trying to get pregnant so this isn't me hoping I see a line.