Baby 8 mos. When excited, or upset flaps both arms in a sorta stiff way in front of him, but at his sides (hope makes sense). Doing since 3 mos. Concer?

Baby flaps both arms. I think there is no problem with what you describe.But be sure to tell the pediatrician at the next visit to check this concen.
Probably not. As long as he is developing normally in other areas--(babbling, crawling. Cooing. Reciprocal conversation, smiling, stranger anxiety. ).