A concerning spot, at first glance...
HOWEVER, when it is 10 years down the track since the melanoma excision, the risk of local recurrence must be small.
Local recurrences usually occur in the first year after removal and are usually due to residual melanoma cells in local lymphatics. They can recur under the graft and around it if the width of excision has not been adequate. Sometimes blood-borne metastases actually localise in skin grafts because of the altered blood supply trapping them there and this can occur much later.
This pigmentation was a seborrhoeic keratosis, which fortuitously