18 days post FUE hair transplant. Did I permanently lose graft or is it just a shed hair? (photo)

Pleas follow the post op instructions for the first two weeks. If you are day 18 then you should be fine.

Based on your images, it cannot be determined if it was a hair graft that or hair shaft that was lost. If you are concerned, follow up with your doctor.

The picture of the graft that you sent can not be fully interpreted due to not being able to see 360 around it and looking for a distinct bulb.  The shafts are clearly pictured but have no bearing on whether the graft will grow or not since the bulb likely stayed in after 18 days.  Unless you have not followed instructions and never washed your hair, leaving this graft stuck in a crusted clump for a few weeks.  

After the procedure you need to careful how you handle the post op care. Shedding of hair shaft with the scabs is normal, but the roots stay under the scalp and grow in later. However if the root also comes out with the scab, it is not normal and will not grow. 

Never pick out the crafts. Always wash your hair daily with gentle finger massage but never use hard pressure on your fingers.