Can I get a gum graft above a veneer? Mine is receded above the margin line, just slightly but noticeable.

If there has been bone loss, it is not predictable to graft at times.  A general rule is 5 mm from bone, so if bone is more than that away from the margin, then a graft may not work.  If it is only slight, then "maybe", so it is best to seek advice from a local periodontist.

It's hard to tell whether you need a gum graft or not, without photos.  Pictures of your teeth will let me know whether you would be better served with a gum graft or if redoing some of your veneers would be the solution.  I'm also interested to know how long you've had your current veneers and how long this recession has been noticeable.  I hope this helps.  Just click save under my photo to ask me more questions in the future.

very difficult to diagnose very useful would be a photo, as the title says, it is good to determine what the cause, if it was before posting and if the cement is the cause, there are variants that can cause this situation. So at least one photo and complement it with the history of what has happened would be very useful. best wishes