This is actually more common than people think, and it can go either way during pregnancy depending on how your baby shifts position or how your uterus is sitting at different stages. It might pop back out again later, or it could stay in, so I would not worry too much about it either way. If it is not causing any pain or discomfort, it is most likely just one of those unpredictable pregnancy body changes lah. That said, if you are ever unsure, just mention it at your next gynae visit for peace of mind.