My Fire-Bellied Toads were quite jumpy and would sometimes hide when I first bought them, particularly the male, but now (just over a week later) they're really active and only hide occasionally- I figured they were just nervous in their new enclosure. Fingers crossed that it's the same for yours Having said this, you should probably still quarantine your frog just in case as my FBTs were active at some point at least in their first few days and more so now whereas yours seems to be much less active than mine.
I hope this helps and your toad is OK