[quote=@Kho]
I think that Lugu has given them the ability to hide their presence, something gods are capable of doing and so could probably be imbued in mortal beings too (though outsiders have an infinite lifespan). Of course, they're not undetectable, gods just won't be able to sense them as easily, unless they are attuned to that sort of thing.
[/quote]

Ah, now it makes sense. :p