Yes, the orbits of Sedna and the other Kuiper Belt objects have perturbations in them that you wouldn’t expect in the absence of the hypothesized new planet. In other words, presumably, a new planet can explain these strange orbits. We haven’t seen the new planet yet, but we can see the gravitational effects it’s having on the other objects near it. It’s not proof there’s a new planet out there, but it’s consistent with it. So they are looking, either to rule it in or rule it out.