Why does my finder sorting options glitch?

I like to organize my files on Finder by date created, but sometimes when I try to do it, instead of normally explaining the date (eg, "Yesterday," "Previous 7 days," "Earlier,") in gray letters above the files: (like this)

The dates ("Yesterday," etc) appears like 'folders' that look like standard Finder folder icons with names next to them. I always use the "view as column" viewing option. I don't have a screenshot, but basically above my files (like above) would be the icon of a folder with the word "Today" "Yesterday" as their names instead of gray text.

It's weird and it occasionally happens but not very often, and I was wondering if I have a virus or does it happen sometimes?

Thank you!