It will probably stay hidden most of time until it's acclimated to your terrarium's conditions. Tiger sals in captivity gradually become conditioned to human presence, associating movement outside the enclosure with food. At this point I would feed it with live food that it can effectively hunt on its own (e.g., crickets), as it may be hesitant to accept other food like worms from your hand.
So after a while you should expect it to become less skittish. That is to say however that this species is, by nature, quite secretive. It's totally normal for them to remain hidden or burrowed most of the time, emerging only to feed and whatnot.
Also, be sure that the terrarium isn't too warm. This species hails from temperate regions and prefers to be cool.
