Don't worry that is more than likely completely normal, these little guys are pretty finicky sometimes.
Can be very stubborn but soon Hunger Will win.
Just make sure you don't leave any uneaten food in the tank because that can cause a serious problem with water quality.
I found the best tool for this job is some small tubing used for aquarium airlines.
Used as a siphon to vacuum up uneaten food or other debris. (Poo)

Just like one of the moderators tagline reads if you take care of the enclosure everything will take care of itself.