bottom of belly suddenly soft?

This morning I realized that the very bottom of my belly is saggy and squishy. This is confusing me because my belly has been tight up until this point. I'm not talking about a pooch after baby, after all this is my second baby. Just randomly, my belly feels softer at the bottom and my stretchmarks don't feel as "tight". I thought maybe because baby dropped but if that were the case, wouldn't it be the top that is soft and squishy? I'm 37 weeks.