Hard to tell with that pic on my phone, but to me it just looks like light bruising. I doubt it’s an infection as you would be able to feel a little warmth radiating from it as well as abnormal amount of itchiness. Could even be just where the artist was trying to add some contrast. I notice the same coloring on the cheek and the upper mandible Just watch it to make sure it’s not an infection. Otherwise enjoy it. It’s a pretty clean piece IMO