I would not worry. When I got my RETF I put him in the quarintine tank and he slept for 8 days straight and then all the sudden he woke and was eating very aggressivly. On Sunday I moved him to his new digs and he has been sleeping since then. Just like MugPro said, they adjust to their new home by sleeping. Give it some time, they should come around.

I would also try to limit the time spent looking in to the tank until they have had time to adjust. The less they feel threatened the sooner they will come out!