confused..

So, my little girl will be 5 weeks old tomorrow. I had her via c-section. I know I was supposed to wait 6 weeks before having sex, but I didn't. Oh well. Don't lecture me on it. I know exactly how kids come about, lol. I stopped bleeding around 2 weeks PP, so we went ahead and had sex. We used a condom EVERY TIME. I made sure of it. I took a pregnancy test just to see if it still came back positive about a week ago (LO was a little over 4 weeks old, at the time) there was a faint line, but I figured it was still just leftover hormones from the pregnancy, so I didn't think much into it. Well, I took another test last night and got this...

It dried before I took the picture, but the line showed up within the time frame. So, do you all think it's leftover hormones? Or a new pregnancy? I just don't see how it's possible to show up on a test, if I am pregnant, seeing as how I'd only be 3 weeks along, if that. I didn't get a faint positive with my daughter until I was 5 weeks along.. Anyone ever had this happen to them before? Any insight would be greatly appreciated! Also, if you don't have anything helpful/nice to say, keep it to yourself, please and thanks!