I was coming through a drive through at a restaurant and I did not see there was a little corner hidden and chipped off the back sidewall tire. I didn't immediately check the tire out till I got back home and I didn't feel anything wrong with the car while I drove it on the highway that night.
I'm so mad at myself for letting this happen as I'm usually careful and I just got both my back tires replaced this past summer and don't drive much.