Don't be worried then. When it becomes a week or longer, then you begin to worry. Also, did you ask your lfs what they were feeding it? You should always do that and get the fish, exactly what they're feeding them.
"The diet of the Lemonpeel Angelfish should include Spirulina, marine algae, high-quality angelfish preparations, mysis or frozen shrimp, and other meaty items. This angelfish requires more algae and seaweed in its diet than most angels."