Winkle, it seems common, don't worry abt it, if small your body will reabsorb it...
Also called subchorionic hematoma, subchorionic bleeding is the accumulation of blood within the folds of the chorion (the outer fetal membrane, next to the placenta) or within the layers of the placenta itself. These bleeds, or clots, can cause the placenta to separate from the uterine wall if they get too large, if they develop in a bad spot, or if they aren’t eventually reabsorbed.
How common is it? A good 20 percent of pregnant women will experience some kind of bleeding early in pregnancy, though it’s often hard to tell what’s causing the problem. Subchorionic hematomas are even harder to pick up because they don’t always result in noticeable spotting or bleeding, especially when they’re small.