2.3 weeks post op Hair Transplant, is it okay to get a spray tan?

Yes but it is always a good idea to follow up and check with your doctor.  I would want to be kept in the loop if you were my patient.

Following hair transplant, it is ok to apply products at the 2-3 week point.  Some would even say sooner than that would be ok.  If you are unsure, ask your doctor for advice.  I would imagine that he will be ok with you getting the spray tan, as the transplanted hair follicles are healed below the skin's surface at this point.

All in all,  you'll want to check with your hair transplant surgeon to confirm. But it should be fine.