Sore stomachs are part of pregnancy. Although it's not so much sore as it is aches. As our bodies get ready for the growing baby it streches and that causes body aches, or a sore stomach. It's one of those things that is a part of pregnancy and it does not last.
It is fairly normal to have a wide variety of aches and pains, especially during the pregnancy. However, if the pain is worrisome, or continues too long, consult your doctor.