I had one at my 22 week scan, and it has moved up now as my uterus has grown. I wouldn't worry too much as most do stretch and move out of the way as the pregnancy progresses.
I sure hope your right :) the recovery time for me has been a week or two. Can't imagine being down for the count four four weeks with four kids.
My pal had tht and had to go for a csection as there was worries tht it would come out before the baby did, she did have the option for a normal birth but decided to b safe and good thing too coz the cord was rapped tight round her baby and she was told if she had it naturally her and the baby could have died
I had a low lying placenta with my current pregnancy and it came up around 29 weeks. I think it's very common for it to start out low lying and then come up on its own.