I thought the school lost my daughter..

I just want to get other mom's opinions on how they would feel. Today was my daughter's first day of kindergarten. I'm super excited to get my daughter I show up 10 minutes early to wait in the pickup line. The students start to line up and I notice I don't see my child. At this point I'm like okay my daughter is short maybe I just don't see her. The teacher comes to the gate and I full blown do not see my child. I asked to the teacher where is my child. She then says my child is a "Bus Rider". Mind you I'm her mother I've never signed my child up for the bus ever. I said no she is not. She has an aid run over to the bus I follow the aid to get my child. Only to be told my child isn't on the bus. I'm in full on panick attack mode 8 months pregnant crying my eyes out. I go inside the office wondering maybe she was sent there for any reason. She isn't in there at all.. I come out and her teacher is walking up with her. From what my daughter said when they leave the teacher calls each student by name to line up but my daughter's name was never called. Mind you my daughter is five and doesn't know better and just stays in the class. My thing is how do you not notice a child still in class. I mean her backpack will still on the post. But the odd thing was they attached a slip to my daughter's back pack stating once again she was a bus rider. When I would've never ever signed my child up for that. Plus you have to pay for it witch I never have. I'm trying to be very forgiving. I know accidents happen absolutely ecpsically the first day of school. But now I'm extremely paranoid they're going to put her on the bus one day and it terrifies me that I won't be able to find her.