Dented looking scales on my BP

[Dano94]

Hi Guys,

Not too sure what these are on my python so I thought I'd ask you. They first appeared about 3 weeks before a shed and are now there after his shed.

http://i1144.photobucket.com/albums/...r/IMG_3837.jpg

That isn't my photo or BP but the markings are exactly the same.

They look dented and I was wondering what they are.

Thanks,

Dan