Could very well be that it's just because you just started dusting.
I think you should know the temperatures in the cage.
It's important to feed/gutload the insects properly. For crickets, roaches, locusts, superworms I recommend using a wide variety of greens such as collards, escarole, endive, dandelion greens, kale, etc and veggies such as carrots, sweet red pepper, squash, zucchini, sweet potato, etc.
It's also recommended that you dust at most feedings with a phosphorous-free calcium powder to help make up for the poor ratio of calcium to phosphorous found in most feeder insects.
Its recommended that you dust twice a month with a vitamin powder that contains a beta carotene (prOformed) source of vitamin. PrOformed sources of vitamin A cannot build up in the system and lead to health issues while prEformed sources can and this leaves it up to you to decide whether the chameleon needs prEformed or not.
It's also recommended that you dust twice a month with a phosphorous - free calcium / D3 powder to ensure that the chameleon gets some D3 without overdosing it and leaving it to produce the rest of the D3 from its exposure to the UVB light. D3 from supplements can build up in the system and lead to overdoses but D3 from exposure to UVB won't likely as long as the chameleon can move in and out of the UVB when it wants to.