new Leopard Gecko feeding

Question
We purchased a leopard gecko for our son three days ago, and in that time he has not eaten.  We are using the meal worms with gut loading powder that was recommended by the pet store, as well as crickets.  Per the store owner, this is the same diet they had while in the store, and it should not be too big for the gecko.  We are just concerned with him not eating.  I am thinking that it could be stress from a new environment but I do not know if there is something else I should be looking at.  The terrarium is kept at about 85 during the day and around 65 or 70 at night.  he has a place to hide, and frankly has not come out at all while at home.  We have not handled him yet because i do not want to stress him any more than the move already has.  We are just concerned with him not eating.  I am thinking that it could be stress from a new environment but I do not know if there is something else I should be looking at.  Please let me know your thoughts, and how long he can go before  this really becomes a serious concern.  Thank you for your help!

Answer
Sounds like everything YOU are doing is good.  Is the food being offered at night?  Leos are nocturnal so that might help, however, 3 days is a LONG time w/o food.  I'd contact the pet store and ask for their opinion AND inform them that it has not eaten at all, and you will be expecting a replacement if it dies or does not eat within the next 48 hours.