Recently I've been seeing these fast moving tiny gray bugs on the soil/roots of some of my orchids (a neo and a psychopsis that are in separate places). And if I lift up a pot I usually find a few scurrying for cover. The biggest is maybe as long as a millimeter, most are smaller.
Was told when I had this worry myself that Springtails aren't anything to worry about though they can signal degraded media. But they're definitely super common.