Mine have already gone out to new homes...
However, I notice yours appears a little shriveled. You have what appears to be razor marks like you may have used parafilm on the graft to hold it down and then used a razor to remove it.
However, the stock itself does not appear to show the hallmarks of parafilm ever being applied as the scaring is not as smooth as it would be if you had used parafilm.
So, it is a bit contradictory the messages I am getting with your graft. I can only assume you have either removed your parafilm in less than 24-48 hours not allowing it to heal properly or those vertical scars on your stock are from some other endeavor.
At any rate, the dark color is not worrisome. The shriveled look however tells me that if the scion has grafted, it is most likely a partial graft and as such it may well do to reintroduce it to a humidity chamber to allow it to plump back up a bit while it heals.
When I graft you graft we graft