Faint test after confirmed pregnancy

Lindsay
Okay so I'm kinda getting myself all freaked out. I need some reassurance. I am 11 weeks pregnant and when I first tested I got the dark line back and now I test this morning. It just lets me know okay babies in there since I don't get an ultrasound for a while. And the line is really faint. Not as dark as it was in the beginning. So now I'm all nervous.. Could this be because the placenta is picking up the extra hormones? 
Little background info. I had a 9 week scan and baby was great heartbeat and all. 
Anybody else ever tested after already knowing their pregnant and see this?