Standing up again

I am pretty sure the activity mat is not supposed to be used this way since the arches aren't too stable but James was being creative in how he uses it. Friday evening I was at the computer and Sean was sitting on the floor with James. He said, " Did you see that?!? Has James pulled up like this before?!?" I looked over and saw James standing up holding on to his activity mat. He had only pulled up and stood up in his crib that morning. Sean said he was sitting on the mat and playing then grabbed onto the arches and pulled himself up from a sitting position. He is so strong and now standing up is his new favorite thing to do!