Until he has time to settle in more, you may want to remove the moss and let the food wander around the cage until he eats it. Some pacs never do well being tong fed, while others do great. Mine is a great eater, but only once in her life has she ever taken anything from tongs.
Not to say you shouldn't keep trying to tong feed, but if you're getting worried you can try just letting the food go until he feels more comfortable taking food from the tongs.

Also, if he keeps not wanting to eat, you may want to put a divider in the 10 gallon until he gets larger. Babies can get freaked out by all the open space in a large enclosure. You can also cover three sides of the tank (or put it in a corner). This makes them feel more secure and he might get braver about taking food from the tongs.