rolling over and then some

Baby Doodle not only rolls over onto his stomach via his left side, he can now roll to the right. And he pulls his knees under him, sticks his butt into the air, and pushes up with his arms. Does this sound like crawling position or what? I think he'll crawl within a week or two. He was really working out last night in the co-sleeper and this morning on the blanket on the floor of the bathroom. Did I mention he can also roll himself back over onto his back? He doesn't do this routinely, but he's done it a few times now. His four month birthday is tomorrow.