My yellow tail Damsel is hiding

Question

I bought a yellow tail damsel yesterday and he is hiding in the rock, he does dart out for food though is this normal for them

Answer 1

 I have a blue yellow tailed damsel as well. First we had him in a 10 gallon tank for about 4 months and have now upgraded to a 40 gallon tank and moved him over. He is now no where to be seen I have searched all over the tank.  Do damsels dig tunnels and burry themselves to help hide?  Should I be concerned