I think the most conservative thing to do is first, see if you can inspect the inside of her mouth at the corners where the temporal gland is. If she'll gape at you take a close look, or at least hold her mouth open with a finger so you can check. Roll her lip back to look for any reddened areas, swelling, or other discoloration. Yes, the crusty stuff can be residue from crushing and chewing an insect but you can gently wipe this away with a wet Q tip. If you see any sign of infection I would take her to a herp vet. Several forum members have successfully treated these infections if caught early so I'd do a thread search on temporal gland infections.
Another thing that might help fight this off is to increase the citrus content of your feeder gutload. Offer your feeders fresh citrus fruit if you don't now. I have read that increasing the citric acid (vit C) in the diet can change the pH of the cham's saliva and that might help her fight off the infection. It won't hurt anyway.