Cousin throwed my baby in the air

I am really angry and worried. A few days ago my cousin visited us for the first time since my baby is born so she doesnt know "our rules". She had my daughter on her lap and the next thing I saw was her throwing her in the air, in a playing way but we dont do it as I am very scared of baby shaken syndrome. I dont really care that many people do it, i dont do that to my child.. I am really worried now about my baby, I mean she seems to be normal but when I just picture this again in my head I want to cry, seriously like why the hell you need to do this to someones child? Please guys tell me I am overreacting...would u be worried?