Squishy bump on kitten's leg?

I am fostering a kitten who just developed a squishy bump on his hind leg today. It is smaller than a dime and there is hair missing from the spot...also the skin on that area looks a little dry. He is playing and eating normally and doesnt seem bothered by my touching the spot. I plan on calling the vet first thing tomorrow morning (obviously), but if there is anyone who has had this experience before and can give me peace of mind until then, that would be appreciated!