Yeah, but it's the difflock slave not the clutch slave (just to be clear).
I think that's one of the ugly ones, since PET doesn't show a gasket (see Main Group 3, Sub Group 05, Illustration 305-15, Part 20 (964 339 775 07).
Dunno what to tell you
If it was me I'd park it, drain the fluid, and pull the slave without undoing the hard line if possible. See if there's an o-ring or something.