Circular bald spot on back of head/behind ear in donor area after a 1,400 FUE filling in my hairline. (Photos)

HT date: 12/15/17. About 2 months post-FUE, I noticed a circular bald spot behind my left ear. 1st thought was shock loss but according to my doc, it normally doesn't manifest this way. I looked up alopecia areata on Wiki and the photo they have looks exactly like my bald spot. My doc (over the phone)said it's probably AR and it's genetic I find it unlikely that I just happened to get it as a 30 year old 2 months post-HT. I never had anything like this before. Is there anything else it could be?