My boa gets creased like that where she is coiled up if she has been lying in the same place for a while. I think it's just like when you sleep in one spot and then get an imprint from the blanket on your face. I can't speak for yours but judging by the picture it looks very similar.
I'm going with the same concept. All my larger boas have the same thing when coiled up tightly for awhile. I wouldn't worry about it too much.