Something Happened With The New Update! Help!

So installed and restarted my computer (it was plugged in charging if that matters, no power surges or anything though). I didn't do these seperately or anything but just clicked the button that said install and restart. Anyways, after when the screen goes dark and I think it's about to restart there's this loud beeping sound I've never heard before, and then it cuts to a loading bar that takes quite a while to load. I thought it was the startup screen but it wasn't. Anyways it then shutdown and restarted, more or less like nothing had happened, however I want to know have I messed up my mac? Please explain.