Don't worry just yet
Chameleons will eat a number of inorganic things. Soil, bark, etc. It's normal, and many think it helps their digestion.
They can also be territorial and are easily upset by changes in their environment, so moving to a new cage might cause a dip in appetite. I know mine didn't like it much when I switched them to their bigger cages. It took them almost a week to get back on their normal feeding schedule.
Try offering different types of bugs to make sure it's not just food boredom. Chameleons are notorious for refusing one food over another periodically (mine will alternately refuse dubias, crickets, and mealworms when they get tired of them).