The donor area is burning and a yellow crust has formed - is this an infection? (photo)

In my opinion you should contact your surgeon as it can be an infection and you should maybe use some antibiotics. your surgeon will advise you about the details and what will be the best for your case.

Burning stinging sensation and yellow crusting is not normal.  You need to see a doctor for a proper exam.

See a doctor as soon as you can. It's possible this is part of your normal healing process, but these are common signs of an infection. If it is infected, you need to address it ASAP.

Follow up with your hair restoration doctor and clinic's post op care department to see what they advise. 

Some people do develop discomfort a week or so after FUE harvest.  However, it is difficult to tell just from a photo without an examination.  I suggest you contact your surgeon now for advice.

This does not look right to me. Go back to see your doctor and get examined to find out if this is an infection