Hi Jean, welcome to the forum. It's refreshing to hear of a Petsmart employee actually interested in knowing more about frogs!

While the age and the size indicate female, don't go by the throat - plenty of males have white or creamish throats - they just have more yellow on the lower parts of their bodies than females.

If the soil has no large particles in it then don't worry - these frogs probably eat all kinds of debris in the wild while trying to catch prey. You have the key to minimising it though - pick her up (come in from behind - Pyxies usually take aim at something not right in front of them, which gives you a warning if you come in from behind) and put her in the bowl, then feed her. That's what I do with all of my pyxies except on days when I am feeding a dusted prey item (so the dust doesn't wash off).

Does she have a name?