First Time for everything

So the kids had a early out from school today. All the early outs this year have been at 1230. So as I was getting ready to leave at around 1220 my cell phone rings. It is the school secretary telling me that the kids were in the office. I ask what the kids did wrong to both be in the office. She said "No the kids didn't do anything-you are late picking them up. School let out at 12:00" I was so embarrassed. I rush over there and was so upset when the kids ask me why I forgot them. I apologized over and over to the office staff and the Principal who was sitting there playing with them.