This is what normally happens to any new fish i add to my tank, they eat spit out, and do this a few times. Perhaps its getting used to new types of foods from that of your lfs?
There are a few reasons why this could be happening:
1. They could, like you said, still be adjusting to new food/tank/tankmates.
2. The food is too big for the fish's mouth. Try breaking it up a little.
3. The food is too hard/crunchy. Get a little cup of tank water and soak it for about 20 seconds for flakes and a minute or so for pellets or hard foods.
4. The fish doesn't like that food.