When I put my hand on my uterus it was very hard. At first I was thinking the baby was rolling too but I doubt it now by the way it felt and it was not just one part.
I thought I had a couple here and there but when I relaxed and thought about it, it kind of felt more like the baby spazzing and trying to stretch out as straight as it could. But I think it is possible since some women do go into labor naturally really early.