Am I pregnant?? Period late 4 days.. took a test and right away….

C

The only line to come up was not pregnant horizontal line after just under a minute I didn’t wait long before I threw it out. I threw it out thinking it was just my period late… coming soon. I went back an hour later and grabbed it out of the trash to see because it’s weird my period would be this late with no signs of it. And here it now reads pregnant. Is this an error and happens after a negative test sits for an hour?