I had the same thing happen to me in a JV game in my first year of umpiring high school ball. The pitcher raised his hand up in the air and kind of wiped his chin with his shoulder as his arms came up and stepped off with his right foot at the same time. The runner from first broke and was picked off. I did not call a balk but the play haunts me to this day. It has never happened again since but I always watch for it. He got me. The offensive team coach never said a word.