[Gecko] Stressed, thin leo Help!

[Lorie McGraw]

Help!
I just got a new male leo in the mail and he arrived so thin and hot, what 
should I do?  I have him in a fresh cage, plain paper, I have not misted 
him.  His tail is down to nothing and his ribs are showing.  Should I try 
feeding him?  Let him be for a while?  The seller mailed him on Monday from 
NY and he arrived here today (Wed) in South Carolina.  It is very hot and 
his box had no airholes.
I have a mister, but I am afraid to because it might shock him too much.

Can a leo lose all of his fat in 2 days?
Help!