yes, it is a concern. it is a type of fungal infection. one of mine had the same thing. you are going to want to isolate the frog and take it to vet listed for exotics, it is hard to convince a vet unfamiliar with the problem or the animal that you know what you need. you will need a prescription of 10% silver sulfadiazine

here is a website with more info from the person who helped me out The Frog Doctor