It is NOT uncommon! I order about 15 western blots a week and I’ve seen false positives at 17 with several in the 12’s and 13’s.
Immediately when I started to read your post I suspected a false positive because people entering UW (Age 18) only 3% are positive for HSV 2.
I’m so glad you did the blot, congratulation on your good sense!
Terri