What Causes Whitening And Lifting Of Skin Graft In Finger?

35 5ft 10 158pds male. had ring finger amputated at last joint towards tip. had skin graft 2 wks ago. past few days graft is lifting at one corner and graft has turned mostly white except very tip wich is transparent to see red through it.question is, is the white normal?dr said top layer would slough away but this layer appears "thick" and as said "lifting" not sloughing. thank you for time and knowlege