Looks as if it could be seeping out around the electrode as in between the electrode shaft and the insulator that helps prevent this from happening. If that's the case the only likely fix is element replacement. Had that to happen on a FF X5 single boiler machine and tried a few different fixes, but nothing effectively sealed it.
With it in operation (be safe of course) did you see exactly where the water was originating from or just spotted that bit of a puddle? The way it looks it could've seeped out and just flowed downward. If it was just around the threads/nut then a possible fix like o-ring replacement and high temp RTV silicone would probably do it.