It's normal, they are often left over vertices. If you want to get rid of them select the unwanted edges or vertices and press "backspace" key on the keyboard, as this will delete your selection but will leave everything around it untouched, contrary to delete that will remove shared geo. You can also look for floating…
I suspect it's 2 point polys. Under that statistics tab, drop down Polygons, By Vertex, then hit the little + beside 2. That'll select all polygons with 2 vertices. You should be able to delete them as per normal.