Swinging arms when excited

Does anyone else's baby swing his/her arms around when they're excited? 4 1/2 months and started doing it yesterday. He was very excited on the playmat, smiling and talking, swinging his arms around and hitting/grabbing the toys. Today he was doing it in his rock n play with a teething toy in his hands. As soon as daddy started talking to him or he got a different toy, he would swing his arms around. It seems like excitement, but google has me freaked the F out.