Hi there, what type of insects do you feed her ? It looks like a possible cricket bite. Either that or she may have just rubbed her nose on the glass or on something in the cage. You can put either a small dab of Neosporin or a dab of raw honey on it. Unpasteurized honey [ like from a health store or a beekeeper ] is a natural antimicrobial. If you DO use raw honey, be sure there are no loose crickets in the tank that would be attracted to the honey on her .
It will probably heal just fine but if it gets worse you might want to have her seen by a qualified reptile vet.